sabulicolous adj. Growing in sandy places.

sac (L. saccus: bag) n. A bag-shaped compartment, as the cavity of an anther or the lower lip of some corollas; a pouch-like structure.

saccate (L. saccus: bag) adj. Having the form of a sac; pouch-like; bag-shaped. Applied to spores and pollens where a separation of the exine layers produces an air sac (saccus). Characteristic of many conifers. Also sacciform.

Saccharomyces (Gr. sakkhar, sakkharos: sugar; mykŕs: fungus) n. An industrially important genus of yeasts. S. cerevisiae, of which there are at least 1000 strains, is used in baking (see baker's yeast), brewing, and wine making; it is also used in the production of single-cell protein and ergosterol, a steroid. The other main yeast used in the production of beer is S. uvarum (or carlsbergensis); it is distinguished from S. cerevisiae by its ability to ferment the disaccharide melibose using alpha-galactosidase, an enzyme not produced by S. cerevisiae.

sacciform (L. saccus: bag; forma: shape) adj. Having the form of a sac. See saccate. Also sacular.

saccular (L. saccus: bag) See sacciform.

sacculate (L. sacculus: small bag) adj. With a saccule, or in the shape of a saccule.

saccule (L. sacculus: small bag) n. A very small sac, small sac-like structure or cavity, as those downgrowths from near edge of epiphragm, between and just inside the teeth of Polytrichum. Also sacculus.

sacculi See sacculus.

sacculus n. (pl. sacculi). See saccule.

saccus (L. saccus: bag) n. (pl. sacci). A sac or pouch. A winglike or bladderlike extension on a pollen grain.

sagittate (L. sagitta: arrow) adj. Shaped like the head of an arrow with the basal lobes pointing downward. Cf. hastate. Also sagittiform.

sagittiform (L. sagitta: arrow; froma: shape) adj. See sagittate.

sago n. A starchy food obtained from the Indonesian sago palms (Metoxylon sagu and M. rumphii), cultivated in Malaysia. The palms, up to 9 m high, take 15 years to mature and are harvested just before flowering. The starchy pith in their stems is extracted, ground, and washed to make flour or pearl sago. The pithy stems of a tropical Asian cycad, Cycas circinalis, also called sago palm, are used as a source of sago. The plant has ornamental fernlike leaves.

Sakmarian n. 1. An age in the Early Permian Epoch, preceded by the Asselian, followed by the Artkinsian, and dated at 281.5 to 268.8 million years ago. Originally it was regarded as the basal Permian age, incorporating the Asselian Age, from which it is now separated. 2. The name of the corresponding eastern European stage, which is roughly contemporaneous with parts of the Rotliegende (western Europe), the upper Wolfcampian (N. America), and the upper Somoholoan (New Zealand).

salicoid adj. Said of a leaf tooth in which the medial vein ends in dark but not opaque persistent spherical callosity, no laterals are involved, perhaps close to a theoid tooth.

salient (L. salire: to jump, to leap) adj. Projecting outward.

salve n. A medicinal ointment that soothes or cools wounds.

salverform (L. salvus: safe; forma: shape, figure, image) adj. Said of a corolla in which the tube is essentially cylindrical, the lobes abruptly spreading; a gamopetalous corolla. Syn. hypocrateriform.

salver-shaped adj. Having a slender tube, expanding suddenly above into a bowl-shaped or spreading border, as in the blossom of the phlox and the lilac. Also salverform, hypocraterimorphous, hypocrateriform.

Salviniaceae n. A family of the phylum Filicinophyta.

samara (L. samara: elm seed) n. A dry single-seeded indehiscent fruit in which the fruit wall hardens and extends to form a long membranous wing-like structure that aids dispersal. Examples are ash, maple and elm fruits. (The wing may be limb-like or envelop the seed and be wafer-like). The sycamore fruit is a double samara and technically a schizocarp. See also achene.

samaroid (L. samara: elm seed; Gr. eid˘: to look like) adj. Samara-like.

sanguine (L. sanguineus: bloody) adj. Blood red. Also sanguineous.

sanguineous See sanguine.

sap n. The juice of a plant; the fluids circulated throughout a plant.

sapid (L. sapidus: that has taste, flavour) adj. With an agreeable taste.

sapling n. A young tree.

sapogenin n. A nonsugar portion of a saponin that is typically obtained by hydrolysis, has either a complex terpenoid or a steroid structure and in the latter case forms a practicable starting point in the synthesis of steroid hormones.

saponaceous (L. sapo, saponis: soap) adj. Soapy, as in a substance or object slippery to the touch.

saponin (L. sapo, saponis: soap) n. Any of a class of glycosides, found widely in plants, that have detergent properties and form a lather when shaken with water. They are especially concentrated in the soapwort (Saponaria officinalis), whose foliage was formerly boiled and used as a soap substitute. Chemically saponins consist of a sugar group (e.g. glucose) linked to a steroid or triterpene group; a related group of compounds, the sapogenins, have no sugar group. Their presence in plants is thought to act as a deterrent to herbivores - they are bitter-tasting and cause gastric irritation if ingested. They are also highly toxic to fish. If injected into the bloodstream they disrupt red cells, through their effects on cell membranes.

sapor (L. sapor: taste, flavour) n. A quality perceptible by taste, e.g. sweetness. The flavor or taste of a plant or plant substance.

saprobe See saprotroph.

saprobiont (Gr. sapros: rotten, mouldy; bios; life) See saprotroph.

sapromyophilous adj. said of a kind of entomophilous pollination, flowers pollinated by flies and with a distinctive syndrome (e.g. purplish color, the odour of carrion or of decay in general).

sapromyophily n. A kind of entomophilous pollination, flowers pollinated by flies and with a distinctive syndrome (e.g. purplish color, the odour of carrion or of decay in general).

sapropel (Gr. sapros: rotten, mouldy; pŕlos: mud) n. An unconsolidated sludge consisting of the decomposed remains of aquatic organisms, especially algae, that accumulates at the bottoms of lakes and oceans.

saprophage n. An organism that lives on decaying organic matter.

saprophyte (Gr. sapros: rotten, mouldy; phyton: plant) n. An organism (typically a bacterium or fungus) deriving its nourishment from dead organic matter, by secreting digestive enzymes into an organic substratum and absorbing the digestion products directly into its cells; such an organism usually lacks chlorophyll. Cf. epiphyte, parasite. Syn. saprotroph.

saprophytic (Gr. sapros: rotten, mouldy; phyton: plant) ad. Feeding from dissolved or decayed organic material, as a saprophyte.

saprotroph (Gr. sapros: rotten, mouldy; trophŕ: food) n. Any organism that feeds by absorbing dead organic matter. Most saprotrophs are bacteria and fungi. Saprotrophs are important in food chains as they bring about decay and release nutrients for plant growth. Cf. parasitism. Syn. saprobe, saprobiont.

sapwood n. The softerpart of wood, between the inner bark and the heartwood. See alburnum.

sarcocarp (Gr. sarx, sarkhos: flesh [of men, animals or plants]; karpos: fruit) n. The fleshy portion (mesocarp) of a fleshy fruit, as the peach, etc.

sarcocaulis See sarcocaulous.

sarcocaulous (Gr. sarx, sarkhos: flesh [of men, animals or plants]; kaulos: stem) adj. With fleshy stems. Also sarcocaulis.

sarcotesta n. The usually parenchymatous outer layer of the integument in some seeds; see also endotesta and sclerotesta.

sarcous (Gr. sarx, sarkhos: flesh [of men, animals or plants]) adj. Fleshy.

sarment (L. sarmentum: bine, vine shoot) n. A long, slender runner.

sarmentaceous See sarmentose.

sarmentose (L. sarmentum: bine, vine shoot) adj. Producing slender prostrate branches or runners. Also sarmentous, sarmentaceous.

sarmentous See sarmentose.

sarmentum (L. sarmentum: bine, vine shoot) n. A slender running stem; runner.

sauveolent adj. Fragrant.

saxatile See saxicoline.

saxicoline (L. saxum, saxi; rock; colere: to inhabit) adj. Living or growing among rocks. Also saxicolous, saxatile.

saxicolous See saxicoline.

saxitoxin n. Neurotoxin found in a variety of dinoflagellates. If ingested, it may cause respiratory failure and cardiac arrest.

scaberulent See scaberulose.

scaberulose (L. diminutive of L. scaber: rough) adj. Slightly rough to the touch, due to the structure of the epidermal cells, or to the presence of short stiff hairs. Also scaberulent, scaberulous, scabrellate, scabrellous.

scaberulous See scaberulose.

scabies See mange.

scabrellate (L. diminutive of L. scaber, scabra, scabrum: rough) See scaberulose.

scabrellous (L. diminutive of L. scaber, scabra, scabrum: rough) See scaberulose.

scabrid (L. scabridus: rough) adj. Slightly roughened; rough to the touch.

scabridulous (diminutive of L. scabridus: rough) adj. Minutely roughened.

scabrose See scabrous.

scabrous (L. scabrosus: rough) adj. With small points or knobs, like a file; scaly, scabby, rough to the touch, due to the structure of the epidermal cells, or to the presence of short stiff hairs. Also scabrose.

scaffold branches The main side branches of a tree, especially a fruit tree.

scalariform (L. scalŠ: ladder, stair; forma: shape) adj. Having a ladder-like pattern; step-like.

scale n. A reduced or rudimentary leaf, e.g. surrounding a dormant bud; a thin flap of tissue, e.g. on the ventral surface of a liverwort thallus and at the base of a stamen in Simaroubaceae; the chaff on the stems of ferns; any thin, flat, scarious structure.

scale leaf Vstigial or scale-like leaf, often with little chlorophyl.

scallop n. One of a continuous series of circle segments or angular projections forming a border.

scalloped adj. Having a margin with rounded scallops. Synonyms: crenate, crenated.

scalpelliform adj. Asymmetric and resembling the blade of a scalpel.

scaly n. Having tiny scales, attached at only one end.

scandent (L. scandere: to climb) adj. Climbing.

scape (L. scapus, shaft [of a pillar], stalk [of a plant]) n. A naked, leafless or without proper foliage peduncle (flowering stalk) arising from ground level, usually from a basal rosette, in acaulescent plants, e.g. the flowering stalk of the dandelion.

scaphoid (Gr. skaphŕ: boat; eid˘: to look like) adj. Boat-shaped.

scapiflorous (L. scapus: stalk [of a plant]; flos, floris: flower) See scapose.

scapiform (L. scapus: stalk [of a plant]; forma: shape) adj. Scape-like but not entirely leafless.

scapose (L. scapus: stalk [of a plant]) adj. Scape-bearing; consisting of a scape. With flowers borne on a scape; scape-like. Also scapiflorous.

scar n. The mark left from a former attachment; the mark left on a seed after detachment from the placenta; the mark left on a stem after leaf abscission.

scarify v. To roughen, score or scrape the hard, outer coating of a seed to assist in the absorption of moisture before germination, a process that many desert wash seeds require.

scariose See scarious.

scarious adj. Tough, thin, dry, membranous, chaffy and semitransparent, not green, scale-like, as some bracts. Also scariose.

scattered adj. Irregularly, and usually sparsely arranged.

Schizaeaceae n. A family of the phylum Filicinophyta.

schizidia See schizidium.

schizidium n. (pl. schizidia) A propagule formed from upper layers of thallus splitting off as scale-like segments from main lobes.

schizo- prefix. Meaning split.

schizocarp (Gr. schizein: to split; karpos, fruit) n. A dry indehiscent fruit formed from carpels that develop into separate one-seeded fragments called mericarps, which may be dehiscent, as in the regma, or indehiscent, as in the cremocarp and carcerulus.

schizogenous (Gr. schizein: to split; genna˘: to produce) adj. Formed by the splitting or separation of tissue.

schizopetalous (Gr. schizein: to split; petalon: leaf) adj. With cut petals.

schopfbaum n. An unbranched woody plant less than about 10 m tall and often with a rather stout trunk and a tuft of large leaves at the top.

sciatica n. Pain or discomfort associated with the sciatic nerve. This nerve runs from the lower part of the spinal cord, down the back of the leg, to the foot. Injury to or pressure on the sciatic nerve can cause the characteristic pain of sciatica: a sharp or burning pain that radiates from the lower back or hip, possibly following the path of the sciatic nerve to the foot.

sciophilous adj. Shade-loving.

sciophyte n. A plant growing in the shade.

scissile (L. scissus: cut, split) adj. Splitting easily.

sciuroid (L. sciurius: squirrel; Gr. eid˘: to look like) adj. Shaped like the tail of a squirrel, as in some grass inflorescences.

scler- (Gr. skleros: hard, dry) prefix. Denoting hardening or thickening.

scleranthia See scleranthium.

scleranthium (Gr. skleros: hard, dry; anthos: flower) n. (pl. scleranthia) An achene enclosed within a hardened calyx tube.

sclereid n. A type of sclerenchyma cell that is shorter than a fibre; its lignified walls typically contain branched pits. Sclereids are abundant in seed coats, nut shells, and in pear fruits.

sclerenchyma (Gr. skleros: dry, hard; en; in; khymos: sap, juice) n. A plant tissue whose cell walls have become impregnated with lignin. Due to the added strength that this confers, sclerenchyma plays an important role in support; it is found in the stems and also in the midribs of leaves. The cell walls contain pits, enabling the exchange of substances between adjacent cells. Mature sclerenchyma cells are dead, since the lignin makes the cell wall impermeable to water and gases. Sclerenchyma cells take the form of fibres or sclereids. Cf. collenchyma; parenchyma.

sclerenchymatous adj. Of or pertaining to the sclerenchyma.

sclero- (Gr. skleros: dry, hard) prefix. Denoting hardening or thickening.

scleroderm n. An internal tissue of thick walled cells forming a cylinder inside the hylodermis; e.g. the stem of Sphagnum. Cf. cortex.

sclerogenous (Gr. skleros: dry, hard; genna˘: to produce) adj. Producing hard or sclerotic tissue.

scleroid (Gr. skleros: dry, hard; eid˘: to look like) adj. Hard or indurated. See sclerotic.

scleromorph (Gr. scleros: hard; morphŕ: shape, form) adj., n. Of, pertaining to, or exhibiting sclerophylly. A plant whose leaves (or stems, if leafless) are hard in texture, usually having thick cuticle and containing many fibres. Also sclerophyllous. Cf. xeromorph.

sclerophyll (Gr. scleros: hard; phyllon, leaf) n. A stiff, firm leaf which retains its stiffness even when wilted. Any woody plant with leathery leaves retaining water.

sclerophyllous (Gr. scleros: hard; phyllon, leaf) adj. With leaves stiffened by sclerenchyma. With stiff, firm leaves; with sclerophylls.

sclerophylly (Gr. scleros: hard; phyllon, leaf) n. The normal development of much sclerenchyma in the leaves of certain plants, as some desert plants, resulting in thickened, hardened foliage.

sclerosis (Gk skleros: hard) n. A hardening or thickening of tissue due to lignification. Any woody plant with leathery leaves retaining water.

sclerotesta n. A stony, sclerenchymatous layer of the testa, usually mesotestal in origin and inside the sarcotesta.

sclerotia See sclerotium.

sclerotic (Gr. skleros: hard) adj. Hardened or thickened; pertaining to or affected by sclerosis. Also scleroid, sclerous.

sclerotium (Gr. skleros: hard) n. (pl. sclerotia) A vegetative, resting, food storage body in certain higher fungi, composed of a compact mass of indurated mycelia.

sclerous (Gr. skleros: hard) adj. Hard, firm, bony. See sclerotic.

scobiform (L. scobis: shaving, scraping: forma: shape) adj. Sawdust-like in appearance; powdery, dusty.

scobina (L. scobina: file, grater, rasp) n. The zigzag rachilla of some grass spikelets

scobinate (L. scobina: file, grater, rasp) adj. With a roughened surface, as though rasped.

scopoletin n. A coumarin.

scorpioid (Gr. skorpios: scorpion; eid˘, to look like) adj. Resembling a scorpion; said of a circinnately coiled determinate inflorescence in which the flowers are two-ranked and borne alternately at the right and left; said of a cymose inflorescence, branching alternately on one side and then the other; a determinate inflorescence with a zigzag rachis; an inflorescence) curled up at the end, and uncurling as the flowers develop. Cf. helicoid.

scorpioid cyme A monochasial cymose inflorescence branching alternately from a bracteol or prophyll on one side of a pedicel and then from one on the other side, the flowers being borne in two rows, the whole more or less zig-zag but also coiled like the tail of a scorpion.

scrobiculate (L. scrobiculus: small pit) adj. Coarsely pitted or furrowed, faveolate.

scrofulous adj. Relating to, affected with, or resembling scrofula.

scrofula n. A form of tuberculosis affecting the lymph nodes, especially of the neck, that is most common in children and is usually spread by unpasteurized milk from infected cows. Also called struma.

scrotiform (L. scrotum: scrotum; forma: shape) adj. Pouch-shaped; hollow, in the form of a sac.

scrubland n. A plant community consisting of shrubs, mixed with grasses and herbs. They may either occur naturally or be the result of human activity. They may be the mature vegetation type in a particular region and remain stable over time, or a transitional community that occurs temporarily as the result of a disturbance, such as fire. A stable state may be maintained by regular natural disturbance such as fire or browsing. It may be unsuitable for human habitation because of the danger of fire.

scurf n. Small bran-like scales.

scurfy adj. Covered with small, bran-like scales.

scurvy n. A disease caused by deficiency of vitamin C, characterized by spongy and bleeding gums, bleeding under the skin, and extreme weakness.

scuta See scutum.

scutate (L. scutum: shield) adj. Shaped like a small shield. Lenticulate, but with an elevated rim. Also scutiform.

scutella See scutellum.

scutellate (L. scutella: small cup) adj. With scutella; saucer-shaped or shield-shaped.

scutelliform (L. scutella: small cup; forma: shape) adj. Saucer-shaped or shield-shaped. As patelliform, but oval rather than round.

scutellum (L. scutella: small cup) n. (pl. scutella) The tissue in a grass seed that lies between the embryo and the endosperm. It is the modified cotyledon of grasses, being specialized for the digestion and absorption of the endosperm; scutellum plus embryo is the germ; it is rich in vitamins. A scale, plate, or any shieldlike formation on a plant, insect, bird, etc., especially one of the horny scales on a bird's foot.

scutiform (L. scutum: shield; forma: shape) adj. Shield-shaped. See scutate.

scutum (L. scutum: shield) n. (pl. scuta) An expanded style tip, as in Asclepias.

scyphiferous adj. Bearing scyphi (cups), used especially when apices are expanded to form cups, e.g. Cladonia fimbriata.

Scythian Originally defined as a stage at the base of the Triassic in the Alps. Now it is generally regarded as a series divided, according to ammonite zones, into four stages. The corresponding Scythian epoch is dated at 245 to 240 million years ago.

sebaceous (L. sebaceus: tallowy) adj. Tallowy or fatty.

secondary gene pool Includes all biological species that will cross with the crop; approximates an experimentally defined cenospecies; gene transfer is possible; hybrids tend to be sterile, chromosomes pair poorly or not at all; some hybrids may be weak and difficult to bring to maturity and recovery of desired types in advanced generations may be difficult.

secondary growth Growth in a plant which does not occur at the tips of the stems or roots. Secondary growth produces wood and bark in seed plants.

secondary leaflet A division of a primary leaflet.

secondary peduncle An inflorescence branch.

secondary tissue The differentiated products of lateral meristems.

secondary wall That part of the cell wall deposited during late expansion growth of the cells with strengthening, etc., functions, and made up of cellulose fibrils, lignin, etc.

secondary xylem The xylem produced by the vascular cambium, see also xylem, and compare with primary and secondary growth.

secretory adj. Relating to or performing secretion.

seculate (L. secula: sickle) adj. Sickle-shaped.

secund (L. secundus: following, follower) adj. Arranged or growing on one side of the axis only, unilateral, as flowers or leaves on a stem.

secundine (L. secundina: secundine [after birth]) n. The, second coat, i.e. the inner integument of the ovule, lying within the primine. In the ripened seed the primine and secundine are usually united to form the testa, or outer seed coat. When they remain distinct the secundine becomes the mesosperm, as in the castor bean. Cf. primine.

sedative adj., n. Having a soothing, calming, or tranquilizing effect; reducing or relieving anxiety, stress, irritability, or excitement. An agent or a drug having a soothing, calming, or tranquilizing effect.

sedge n. A perennial monocotyledonous plant with rhizomatous or creeping rootstocks, solid triangular stems, and grass-like leaves. Sedges belong to the genus Carex, with over 1,000 species widely distributed throughout the temperate, Arctic, and Antarctic regions of the world. The family Cyperaceae, to which they belong, contains over 4,000 species, some of which are referred to as reeds or even 'grasses'. They have little ornamental or economic value, though C. arenaria, from Europe and Siberia, is useful for stabilizing loose sands and grows mostly on sea-shores. Sweet sedge, Acorus calamus, is a member of the arum family and is botanically unrelated to the true sedges.

seed n. The structure in angiosperms and gymnosperms that develops from the ovule after fertilization. Occasionally seeds may develop without fertilization taking place (see apomixis). The seed contains the embryo and nutritive tissue, either as endosperm or food stored in the cotyledons. Angiosperm seeds are contained within a fruit that develops from the ovary wall. Gymnosperm seeds lack an enclosing fruit and are thus termed naked. The seed is covered by a protective layer, the testa. During development of the testa the seed dries out and enters a resting phase (dormancy) until conditions are suitable for germination. Annual plants survive the winter or dry season as seeds. The evolution of the seed habit enabled plants to colonize the land, since seed plants do not depend on water for fertilization (unlike the lower plants).

seed coat The outer covering of the seed, from the integuments of the ovule.

seed fern Extinct fern-like plants that bore seeds on the frond.

seed leaf See cotyledon.

seed stalk The funiculus.

segment (L. segmentum: segment) n. A part or sub-division of a divided organ; one of a group of similar organs named collectively, e.g. one petal is a segment of a corolla; a division of a plant organ such as one of the two parts of a bifid leaf.

segmentation n. The division into parts.

segregate n. adj. An individual or class of individuals differing in one or more genetic characters from the parental line usually because of segregation of gene. Separated; isolated.

segregation n. The separation of paternal from maternal chromosomes at meiosis and consequent separation of genes leading to the possibility of recombination in the offspring.

sejugous (L. sex: six; jugum: yoke) adj. With six pairs of leaflets.

Selaginellaceae n. A family of the phylum Filicinophyta.

select-cross See select-crossing.

select-crossing Similar to backcrossing except that a different ecurrent parent is chosen each generation or each time a cross is made; used in tomato breeding (among others) for obtaining resistance to certain diseases, such as brown root ot.

selection (L. selectio, selectionis: choice, sorting) n. Process which favors one feature of organisms in a population over another feature found in the population. This occurs through differential reproduction - those with the favored feature produce more offspring than those with the other feature, such that they become a greater percentage of the population in the next generation.

seleniferous (Gr. selŕnŕ: moon; ferre: carrying) adj. Bearing selenium.

selenophyte (Gr. selŕnŕ: moon; phyton: plant) n. A plant that grows on seleniferous soil and takes up selenium from these soils.

self-compatible adj. Capable of self-fertilization.

self-fertilization n. Fusion of male and female gametes (sex cells) produced by the same individual. Self-fertilization occurs in bisexual organisms, including most flowering plants, numerous protozoans, and many invertebrates. Cf. cross-fertilazation.

self-fertile adj. Able to be pollinated by its own flowers.

self-fertility n. The capability of producing seed upon self-fertilization.

self-fertilizing See self-fertility, self-fertilization.

self-incompatibility n. The genetically controlled physiological hindrance to self-fruitfulness. See self-incompatible.

self-incompatible adj. Incapable of self-fertilization. Not capable of self-pollination.

self-pollinate adj. See self-pollination.

self-pollinated adj. See self-pollination.

self-pollinating adj. See self-pollination.

self-pollination n. Transfer of pollen from the anthers to the stigma of the same flower or to the stigma of another flower on the same plant.

selliform adj. Saddle-shaped.

semelparity n. The occurrence of a single act of reproduction during an organism's lifetime. Most semelparous species produce very large numbers of offspring when they do reproduce, and normally die soon afterwards. Examples include the Pacific salmon and the pine looper moth. Many plants are semelparous, or monocarpic. Repeated reproduction is called iteroparity.

semelparous adj. See semelparity.

semen (L. semen: seed) n. A seed.

semi- (L. semi-: half) prefix. Meaning half, partly or almost.

semicarpous (L. semi-: half; Gr. karpos: fruit) adj. With ovaries of carpels partly fused, the style and stigmas separate.

semicraspedodromous adj. Said if a pinnate venation, craspedodromous in particular, in which the secondary veins branch just inside the margin, one of the branches terminating at the margin, the other joining the superadjacent secondary vein.

semiepiphytic adj. See semi- and epiphytic.

semilunate (L. semi-: half; lune: moon) adj. Tending towards the form of a crescent moon.

seminiferous (L. semen, seminis: seed: ferre: to carry) adj. Seed-bearing.

semiparasite (L. semi-: half; parasitus: parasite) adj. Partly parasitic and partly photosynthetic. See hemiparasite.

semi-terete (L. semi-: half; teres, teretis: round, smooth) adj. Flat on one side, terete on the other.

semperflorous (L. semper: always; flos, floris: flower) adj. Flowering throughout the year.

senecionine n. A pyrrolizidine alkaloid.

sensitive adj. Responsive to touch

sepal (Gr. skepas: covering, shelter; [pe]talon: leaf) n. Any of the leaf divisions of the calyx. When a calyx consists of but one part, it is said to be monosepalous; when of two parts, it is said to be disepalous; when of a variable and indefinite number of parts, it is said to be polysepalous; and when the parts are more or less united, it is said to be gamosepalous. Sepals are considered to be modified leaves with a simpler structure. They are usually green and often hairy but in some plants, e.g. monk's hood, they may be brightly coloured.

sepaline (Gr. skepas: covering, shelter; [pe]talon: leaf) adj. Referring to sepals.

sepaloid (Gr. skepas: covering, shelter; [pe]talon: leaf; eid˘: to look like) adj. Like a sepal, in color and texture.

septa See septum.

septate (L. septatus: surrounded by a fence) n. Divided internally by partitions; having or divided by a septum or septa.

septenate (L. septem: seven) adj. With parts in sevens.

septicidal (L. septum, division; caedere, to cut or divide) adj. Dividing through middle of ovary septa; dehiscing or breaking open at a natural dividing line. Cf. loculicidal and poricidal.

septiferous (L. septum: fence, partition; ferre: to carry) adj. With a septum or septa.

septifolious (L. septem: seven; folia: leaf) adj. With seven leaves or seven leaflets.

septifragal (L. septum: fence, partition; fractor: fracture) adj. Of the dehiscence of a fruit, when the valves or backs of the carpels break away leaving the septa intact. Describing a capsule that is dehiscing through the partitions and between the cells.

septum (L. septum: fence, partition) n. (pl. septa) A partition separating two cavities or masses of tissue, as in fruits, as the partitions separating the locules of an ovary.

seral adj. Of or pertaining to a sere.

sere n. The series of changes occurring in the ecological succession of a particular community.

seriate (L. seria: line, sequence) adj. In rows or whorls, e.g. uniseriate, biseriate, triseriate, multiseriate; applied to adjacent rows of leaf cells, or to ranks of leaves on stem.

seriately adv. See seriate.

seriation n. See seriate.

sericate (L. sericum: silk) adj. Silky, sericeous. Also sericeous.

sericeous (L. sericum: silk) adj. Silky; covered with silky hairs. Also sericate.

series (L. series: line, sequence) n. The major subdivision of a system, and the chronostratigraphic equivalent of an epoch. It denotes the layers of strata or the body of rock formed during one epoch. A series may itself be divided into stages. When used formally the initial letter of the term is capitalized, e.g. Lower Cretaceous Series.

serotinal (L. serotinus: tardy, late) adj. Pertaining to or occuring in late summer. Also serotinous.

serotinous (L. serotinus: tardy, late) adj. Remaining closed on the tree with seed dissemination delayed or occurring gradually; late in flowering or leafing; with flowers developing after the leaves are fully developed. Also serotinal. Syn. serotinal.

serotonin n. An organic compound, formed from tryptophan and found in animal and human tissue, especially the brain, blood serum, and gastric mucous membranes, and active as a neurotransmitter and in vasoconstriction, stimulation of the smooth muscles, and regulation of cyclic body processes.

Serpentine see serpentine.

serpentine adj. refers to soils that are low in calcium and high in magnesium and iron, derived from greenish or gray-green rocks that are essentially magnesium silicate, other characteristics of which are a high nickel and chromium content, and a low content of nutrients such as nitrogen.

Serpukhovian 1. The final epoch in the Mississippian, comprising the Pendleian, Arnsbergian, Chokierian, and Alportian Ages (these are also stage names in western European stratigraphy). The Serpukhovian is preceded by the Visean, followed by the Bashkirian (Pennsylvanian), and dated at 332.9 to 322.8 million years ago. 2. The name of the corresponding eastern European series, which is roughly contemporaneous with the upper Chesterian (N. America) and Namurian A (western Europe).

serra (L. serra: saw) n. (pl. serrae) A tooth of a serrate leaf.

serrae See serra.

serrate (L. serratus: shaped like a saw, toothed) adj. Notched on edge like a saw; having sharp notches along the edge pointing toward the apex; as, a serrate leaf. When a serrate leaf has small serratures upon the large ones, it is said to be double serrate, as in the elm. A serrate-ciliate leaf is one having fine hairs, like eyelashes, on the serratures. A serrate-dentate leaf has the serratures toothed. Also serrated. The leaves of Vaccinium angustifolium are serrate.

serrated (L. serratus: shaped like a saw, toothed) adj. Having a notched edge or sawlike teeth. Also serriform, serrate.

serration (L. serratus: shaped like a saw, toothed) n. A serrated margin; one of the teeth along a serrated margin; a serrated condition.

serriform (L. serra: saw; forma: shape) adj. Ressemblng the nothced edgae of a saw. Also serrated.

serrulate (L. serrula: small saw) adj. Toothed along the margin with minute, sharp, forward-pointing teeth. Finely serrate. Also serrulated.

serrulated See serrulate.

serrulation (L. serrula: small saw) n. A serrulate margin; one of the teeth along a serrulate margin; a serrulate condition.

sesquilepidous adj. Of a peristome having a 2:3 peristome number, i.e. two cell columns in the primary peristomial layer opposite three in the inner peristome layer, and is characteristic of the Haplolepideae.

sesquiterpene See sesquiterpenes.

sesquiterpenes n. pl. A terpene with 3 isoprene units. See terpenes.

sessile (L. sessilis: on what one can sit, sessile) adj. Sitting directly on base withous support, stalk, pedicel, petiole, peduncle or seta; attached or stationary as opposed to free living or motile; when applied to a stigma, indicates that the style is absent, the stigma being 'sessile' on the ovary.

seston n. Particulate matter suspended in sea water.

seta (L. seta, bristle) n. (pl. setae) A bristle-like structure or stiff hair; in Bryophyta, the stalk portion of a sporophyte plant body, holding the spore capsule.

setaceous (L. seta: bristle) adj. Bristly; set with bristles; consisting or having bristles.

setae See seta.

setiferous (L. seta: bristle; ferre: to carry) adj. Bristle-bearing. Also setigerous.

setiform (L. seta: bristle; forma: shape) adj. Bristle-like

setigerous (L. setiger: bristling with hairs) adj. Having setae or bristles. Also setiferous.

setose (L. setosus: hair covered) adj. Bristly. Covered with bristles; terminating gradually in a fine sharp bristle.

setula v. (pl. setulae) See setule.

setulae See setula.

setule (L. setula: small bristle) n. A small, short, blunt bristle.

setulose (L. setula: small bristle) adj. Covered with minute bristles.

sexine n. The outer, sculptured layer of the exine, which lies above the nexine, sexine 1, the innermost layer, columellae; sexine 2, tectum; sexine 3, sculpture elements, sexine 5, outermost layer of the sexine, although usually there are three layers.

sexual reproduction A form of reproduction that involves the fusion of two reproductive cells (gametes) in the process of fertilization. Normally, especially in animals, it requires two parents, one male and the other female. However, most plants bear both male and female reproductive organs and self-fertilization may occur, as it does in hermaphrodite animals. Gametes are formed by meiosis, a special kind of cell division in the parent reproductive organs that both reassorts the genetic material and halves the chromosome number. Meiosis thus ensures genetic variability in the gametes and therefore in the offspring resulting from their subsequent fusion. Sexual reproduction, unlike asexual reproduction, therefore generates variability within a species. However, it depends on there being reliable means of bringing together male and female gametes, and many elaborate mechanisms have evolved to ensure this.

sheath n. The portion of an organ which surrounds, at least partly, another organ, as the leaf base of a grass surrounds the stem (culm).

sheathing adj. Forming a sheath, as the leaf base of a rass forms a sheath as it surrounds the stem.

shoot n. Usually, the above ground portion of a plant, bearing the leaves, that shoots out from the main stock. Contrast with root.

short-day plant A plant requiring less than 12 hours of daylight in order for flowering to occur.

shrub n. A woody plant less than 5 metres high, either without a distinct main axis (i.e. with several trunks), or with branches persisting on the main axis almost to its base.

shrubby adj. Of or resembling a shrub.

shrublet n. A small, dwarf shrub.

sialagogic adj. See sialagogue.

sialagogue (Gr. sialon: saliva; ag˘geus: driver, guide) n. A drug or other agent that increases the flow of saliva.

Siegenian n. 1. An age in the Early Devonian epoch, preceded by the Gedinnian, followed by the Emsian, and dated at 401 to 394 million years ago. 2. The name of the corresponding European stage, which is roughly contemporaneous with the Merionsian (Australia), and the upper Helderbergian, Deerparkian, and lower Onesquethawian (N. America).

sieve cell A phloem conducting cell type in all vascular plants except angiosperms.

sieve element A cell in phloem tissue involved in the longitudinal conduction of food materials.

sieve plate The area of the wall of a sieve tube element that contains several to many perforations that permit cytoplasmic connections between sieve tube cells.

sieve tube cell In angiosperms, a specialized cell derived from the same parent cell as the closely associated companion cell immediately adjacent to it; sieve tube cells are elongated cells with sieve plates; sieve tube cells form sieve tubes through which photosynthate is transported.

sieve tube plastid A plastid in the sieve tube usually with starchy or proteinaceous inclusions.

sigmoid (Gr. sigma: the letter sigma; eid˘: to look like) adj. S-shaped; doubly curved, like the letter S.

Silesian n. The Upper Carboniferous sub-system in western Europe, underlain by the Dinantian, and comprising the Namurian, Westphalian, and Stephanian series. It is dated at 332.9 to 290 miilion years ago and is roughly contemporaneous with the uppermost Mississippian (Serpukhovian Series) plus the Pennsylvanian.

silica n. Amorphous silicon dioxide (glass). It is a structural component in many organisms, such as diatoms and horsetails.

siliceous adj. Relating to, or containing silica.

silicicolous adj. Growing on sandstone or other siliceous rock. Cf. saxicolous.

silicious See siliceous.

silicle (L. silicula: small silique) n. A dry, dehiscent fruit of the Cruciferae (Brassicaceae), typically less than twice as long as wide, with two valves separating from the persistent placentae and septum (replum); a short silique.

silicula n. A short siliqua, not more than twice as long as its width. A type of capsule formed from a bicarpellary ovary. It is longitudinally flattened and divided lengthwise into two cavities (loculi). It is broader than a siliqua. Examples include the fruits of Alyssum and candytuft.

silification A type of fossilization in which silica (SiO2) infills intercellular spaces (permineralization) or replaces the cell walls (petrifaction).

siliqua n. (pl. siliquae) See silique.

siliquaceous adj. See silique.

siliquae See siliqua.

silique (L. siliqua: pod) n. (pl. siliquae or siliques) The long, dehiscent narrow pod (fruit) of plants of the mustard family, Cruciferae (Brassicaceae), typically more than twice as long as wide, formed from a superior ovary of two carpels, with two parietal placentas and divided into two loculi by a false septum (replum) between the placentas, with valves which fall away from a frame bearing the seeds. Syn. siliqua. See also lomentum.

siliquose (L. siliqua: pod) adj. Bearing siliques; ressembling a silique or silicle. Syn. siliquous.

siliquous See siliquose.

silk n. The hair-like styles in maize.

silky adj. Silk-like in appearance or texture; sericeous

silt n. A sedimentary material consisting of very fine particles intermediate in size between sand and clay.

Silurian n. Third (439 to 408.5 million years ago) of six periods of the Palaeozoic era. The end of the period is marked by the climax of the Caledonian orogeny and the filling of several Palaeozoic basins of deposition.

silvicolous adj. Growing in or inhabiting woodlands.

simple (L. simplus: simple, one, unique) adj. Undivided as a leaf blade which is not separated into leaflets (though the balde may be deeply lobed or cleft); single, as a pistil composed of only one capel; unbranched, as a stem or hair.

simple fruit A fruit developed from a single ovary.

simple leaf A leaf with an undivided blade.

simple pore Air pore bordered only by superficial cells.

single cross A cross between two different genotypes, usually two inbred lines, in plant breeding.

simple-craspedodromous adj. Said of pinnate venation, a variant of craspedodromous in which the secondary veins and their branches terminate at the margins, often as teeth.

sinistrorse (L. sinistrorsus: to the left) adj. Turned to the left, rising towards the left, or spirally arranged to the left, as in the leaves on some stems. Cf. dextrorse.

sinuate (L. sinuatus: madde bent, made curved, wavy) adj. Having a wavy margin, as some leaves. Cf. undulate or repand.

sinuolate adj. Minutely wavy.

sinuous (L. sinuosus: bent, curved, wavy) adj. Of a wavy or serpentine form.

sinuously adv. See sinuous.

sinus (L. sinus: curvature, winding, fold) n. The rounded depression between two consecutive lobes, as of a leaf; a notch or depression in the margin of an organ, such as a leaf or petal.

siphonal adj. Said of hyphal compartments without septa having many nuclei.

siphonostele (Gr. siphon: tube; stŕlŕ: stele) n. When a plant's vascular tissue develops as a central cylinder, it is said to have a siphonostele; a siphonostele has a pith in the center. See also stele.

syrphid See syrphids

syrphids n. pl. Flies in the Diptera family Syrphidae are commonly known as hoverflies, flower flies, or Syrphid flies. As their common names suggest, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores and prey on aphids, thrips, and other plant-sucking insects. Aphids alone cause tens of millions of dollars of damage to crops worldwide every year; because of this, aphid-feeding hoverflies are being recognized as important natural enemies of pests, and potential agents for use in biological control. Some adult syrphid flies are important pollinators. About 6,000 species in 200 genera have been described. Hoverflies are common throughout the world and can be found on every continent except Antarctica. Hoverflies are harmless despite their mimicry of the black and yellow stripes of wasps, which act to ward off predators.

sister group The two clades resulting from the splitting of a single lineage.

skiophilous adj. Of plants of shaded habitats.

skiophytic adj. Shade loving. Cf. photophytic.

Skythian See Scythian.

smoke point The temperature at which frying oils commence to emit a bluish-coloured smoke showing that they are beginning to decompose.

smooth adj. With an even surface; not rough to the touch.

sobol (L. soboles: shoot) n. An elongated caudex of branches; a shoot arising from the base of a stem or from the rhizome. Also sobole.

sobole See sobol.

soboliferous (L. soboles: shoot; ferre: to carry) adj. Of or pertaining to sobols; bearing sobols.

socket n. A hollowed area formed to receive an articulating part.

sole n. That end of the carpel most distant from the apex.

solitary (L. solitarius: isolated, solitary) adj. Occurring singly and not borne in a cluster or group.

solitary bee See solitary bees.

solitary bees Solitary bees are solitary in the sense that every female is fertile, and typically inhabits a nest she constructs herself. There are no worker bees for these species. Solitary bees typically produce neither honey nor beeswax. Solitary bees are important pollinators, and pollen is gathered for provisioning the nest with food for their brood. Often it is mixed with nectar to form a paste-like consistency. Some solitary bees have very advanced types of pollen carrying structures on their bodies. A very few species of solitary bees are being increasingly cultured for commercial pollination. Solitary bees are often oligoleges, in that they only gather pollen from one or a few species or genera of plants (unlike honey bees and bumblebees which are generalists). In a very few cases only one species of bee can effectively pollinate a plant species, and some plants are endangered at least in part because their pollinator is dying off. Solitary bees create nests in hollow reeds or twigs, holes in wood, or, most commonly, in tunnels in the ground. The female typically creates a compartment with an egg and some provisions for the resulting larva, then seals it off. A nest may consist of numerous cells. When the nest is in wood, usually the last (those closer to the entrance) contain eggs that will become males. The adult does not provide care for the brood once the egg is laid, and usually dies after making one or more nests. The males typically emerge first and are ready for mating when the females emerge. Providing nest boxes for solitary bees is increasingly popular for gardeners. Solitary bees are either stingless or very unlikely to sting (only in self defense, if ever). While solitary females each make individual nests, some species are gregarious, preferring to make nests near others of the same species, giving the appearance to the casual observer that they are social. Large groups of solitary bee nests are called aggregations, to distinguish them from colonies. In some species, multiple females share a common nest, but each makes and provisions her own cells independently. This type of group is called communal and is not uncommon. The primary advantage appears to be that a nest entrance is easier to defend from predators and parasites when there are multiple females using that same entrance on a regular basis.

somatic (Gr. s˘matikos: corporal, bodily) adj. Relating to all the cells of an animal or plant other than the reproductive cells. Thus a somatic mutation is one that is not heritable.

somatogamy n. The fusion of somatic cells or hyphae involving plasmogamy but not karyogamy.

soralia See soralium.

soralium n. (pl. soralia) A group of soredia; a decorticate area on a lichen thallus where soredia are produced.

Sordaria n. A genus of the phylum Ascomycota.

sordid (L. sordidus: dirty, insignificant) adj. Of a dull, dingy, or muddy color.

soredia (Gr. s˘ros: heap) See soredium.

sorediate adj. With soredia.

soredium n. (pl. soredia) A microscopic clump of algal cells surrounded by the hyphae of fungi, occurring on the surface of the thallus and functionning in vegetative reproduction. A specialized asexual reproductive unit of lichens consisting of a mass of algal cells surrounded by fungal hyphae.

sori See sorus.

sorose See sorosis.

sorosis (Gr. s˘ros: heap) n. A type of fleshy composite fruit formed from an entire inflorescence spike. Mulberry and pineapple fruits are examples. Also sorose.

sorus (Gr. s˘ros: heap) n. (pl. sori) Any of the spore-producing structures on the undersurface of a fern frond, visible as rows of small brown dots, i.e. a discrete group of sporangia. A reproductive area on the thallus of some algae, e.g. Laminaria. Any of various spore-producing structures in certain fungi or lichen.

sp. Abbreviation for species.

spadiceous (L. spadix, spadices: palm branch) adj. Spadix bearing; spadix-like.

spadices See spadix.

spadix (L. spadix: palm branch) n. (pl. spadices) A racemose inflorescence, a flowering shoot (a type of spike) with a large fleshy floral axis bearing small, usually unisexual, flowers, i.e. a spike with small flowers crowded on a thickened axis. It is protected by a large petal-like bract, the spathe, and is characteristic of plants of the family Araceae (e.g. calla lily).

spananthus adj. With few flowers

spasmolytic adj., n. (Of) preparation that can ease cramps or spasms. See Antispamodic.

spathaceous (Gr. spathŕ: spatula. flat blade) adj. Having a spathe, or having the nature of a spathe. Also spathose, spathous.

spathe (Gr. spathŕ: spatula, flat blade) n. A large leaflike part (bract) or pair of such, subtending and often enclosing a flower cluster (inflorescence) especially a spadix.

spathella (diminutive of Gr. spathŕ: spatula. flat blade) n. A closed membranous sac which envelopes the immature flower in some Podostemaceae, rupturing irregularly as the pedicel elongates at anthesis. An archaic term referring most commonly to the lemma of a grass flower, but occasionally referring to a glume of a grass spikelet.

spathellula (diminutive of L. spathula: spatula) n. The palea of a grass flower.

spatheole n. A small or secondary spathe.

Spathian n. The final stage of the Scythian Epoch, preceded by the Nammalian.

spathiform (Gr. spathŕ: spatula. flat blade; l. forma: shape) adj. With the form of a spathe.

spathose See spathaceous.

spathous See spathaceous.

spathulate (L. spathula: spatula) See spatulate.

spatulate (L. spatula: spatula) adj. Shaped like a spatula or spoon, gradually widening distally and with a rounded tip, as some leaves; broad at the tip and narrowed towards the base. Also spathulate.

speciation n. The evolution of a new species from an existing species.

species (L. species: type, species) n. A group of interbreeding individuals, not interbreeding with another such group, being a taxonomic unit including two names in binomial nomenclature, the generic name and specific epithet, similar and related species being grouped into a genus. A category of classification lower than a genus or subgenus and above that of a subspecies or variety; a group of plants that possesses one or more characters in common distinguishing is from other groups and does or may interbreed and reproduce its characters in offspring, exhibiting only minor variations bridged over by differences ascribable to age, sex, polymorphism, individual peculiarity, or accident or selective breeding by man; species in a small genus will be separated by relatively large differences in characters, whereas species in a large genus are usually separated on the basis of very small differences that would be ignored in the former; interpretation of species limits depends largely on individual judgment; opinions among botanists differ widely in regard to polymorphic taxa or apomicts which have disparate morphological characters but hybridize freely; classical, or Linnaean, species are based on morphological (presumably constant) differences, biological species, or reproductive isolation.

specific adj. Of or pertaining to a species.

specifically adv. See specific.

speiranthy (Gr. speira: spiral; anthos: flower) n. The condition of having twisted flowers

spermatia See spermatium.

spermatid (Gr. sperma, spermatos: seed) n. One of the cells that results from the meiotic division of a spermatocyte and mature in spermatozoa; a developing spermatozoid.

spermatium (Gr. sperma, spermatos: seed) n. (pl. spermatia) The non motile male gamete of a red algae; a minute, colorless cell, believed to be a male reproductive body, developed within spermogonia.

spermatocyte (Gr. sperma, spermatos: seed; kytos: what covers) n. A cell which, by meiosis, gives rise to sperm cells. A male germ cell (primary spermatocyte) that gives rise by meiosis to a pair of haploid cells (secondary spermatocytes) which give rise in turn to spermatids.

Spermatophyta (Gr. sperma, spermatos: seed; phyton: plant) n. A major division of the plant kingdom, characterized by reproducing by seed and subdivided into the Gymnospermae and Angiospermae (gymnosperms and angiosperms) and now included in the Tracheophyta, the vascular plants.

spermatophyte (Gr. sperma, spermatos: seed; phyton: plant) n. Any plant that reproduces by seeds rather than spores. Spermatophytes include the gymnosperms (conifers, etc.) and the angiosperms (flowering plants), which were formerly classified together in the division Spermatophyta but are now assigned to separate phyla (or divisions). Also spermophyte.

spermatozoid (Gr. sperma, spermatos: seed; z˘on: animal; eid˘: to look like) n. The motile (by anterior cilia) male gamete of algae, fungi, bryophytes, clubmosses, horsetails, ferns, and certain gymnosperms. Spermatozoid usually develop in an antheridium but in certain gymnosperms, such as Ginkgo and Cycas, they develop from a cell in the pollen tube. Syn. antherozoid.

spermatozoon (Gr. sperma, spermatos: seed; z˘on: any living being) n. (pl. spermatozoa) A mature male reproductive cell. One of the minute, usually actively motile, gametes in semen; which serve to fertilize the ovum.

spermogonia Se spermogonium.

spermogonium (Gr. sperma, seed; gonos: generation) n. (pl. spermogonia) One of the cup-shaped or flask-shaped receptacles in which the spermatia of certain thallophytic plants are produced. One of the undifferentiated germ cells giving rise to spermatocytes.

spermophyte (Gr. sperma: seed) See spermatophyte

sphagnous adj. Pertaining to, abounding in, or consisting of sphagnum.

sphagnum n. Any of various pale or ashy mosses of the genus Sphagnum, the decomposed remains of which form peat.

Sphagnum (Gr. spaphgnos: moss...) A widely distributed genus of mosses (over 300 species), called bog or peat moss, forming dense raised clumps in bogs and other waterlogged places. Green to dark red in colour and up to 30 cm high, the fine stems bear clusters of threadlike branches, densely clothed with tiny leaves, and globular spore capsules. The ability of the stems and leaves to retain water (up to 20 times the weight of the plant) is responsible for the outstanding ability of these mosses to drain very wet ground and form bogs. The dead remains of the plants accumulate to form peat-an important fuel and ingredient of horticultural composts. Family: Sphagnaceae.

sphenoid (Gr. sphŕn: wedge; eid˘: to look like) adj. Wedge-shaped; cuneate.

Sphenophyta A phylum of tracheophyte plants, the only living members of which are the horsetails (Equisetum). Horsetails have a perennial creeping rhizome supporting erect jointed stems bearing whorls of thin leaves. Spores are produced by terminal conelike structures. The group has a fossil record extending back to the Palaeozoic with its greatest development in the Carboniferous period, when giant tree forms were the dominant vegetation with the Lycophyta. Syn. Equisetopsida.

sphenopsid n. Any of a class (Sphenopsida or Sphenophyta) of the tracheophytes characterized by jointed ribbed stems, small leaves usually in whorls at distinct stem nodes, and sporangia in sporangiophores and made up of the equisetums and extinct related forms.

spherical (L. sphŠricus: circular) adj. A three-dimensional, isodiametrical structure, round in outline. Syn, globose.

spheroid (Gr. sphaira: sphere; eid˘: to look like) adj. Spherical with slightly flattened ends.

spheroidal (Gr. sphaira: sphere; eid˘: to look like) adj. Almost spherical, but elliptical in cross-section

spicate (L. spicatus: furnished with spikes) adj. Having the form of a spike. Arranged in a spike; spike-like.

spiciform (L. spica: spike; forma: shape) adj. An inflorescence with the general sappearance, but not necessarily the structure, of a true spike.

spicula n. (pl. spiculae). See spicule.

spiculae See spicula.

spicular See spiculate.

spiculate (L. spicula: small spike) adj. Spicule-like; bearing spicules. Also spicular.

spicule (L. spicula: small spike) n. A small, slender, sharp-pointed piece, usually on a surface; a small spike of flowers; a short, pointed, epidermal projection. Also spicula.

spiculiform adj. With the form of a spicule.

spiculose See spiculate.

spiculum n. (pl. spiculae). See spicule

spike (L. spica: spike, ear of corn) n. A usually unbranched, elongated, simple, indeterminate type of racemose inflorescence in which stalkless (sessile) or subsessile flowers or spikelets, arise from an undivided floral axis, and mature from the bottom upwards, as in plantain and Orchis. In the family Gramineae (Poaceae, sedges and grasses) the flowers are grouped in clusters called spikelets, which may be arranged to form a compound spike (as in wheat). Cf. raceme.

spikelet (L. spicula: small spike) n. A small spike of a large one; a subdivision of a spike; a unit of the inflorescence in grasses, sedges and some other monocotyledons, consisting of one to many flowers and associated glumes. Syn. earlet.

spikiform adj. Spike like.

spiladophilous adj. Clay-loving; dwelling on clay.

spindle n. A structure formed from microtubules in the cytoplasm of cells at the beginning of the metaphase stage of cell division (see meiosis; mitosis). Two poles become established at diametrically opposite points close to the nucleus. The spindle microtubules, or 'fibres', radiate from each pole towards the opposite one and diverge to their greatest extent midway between. This widest part of the spindle is the equator. Chromosomes are attached by their centromeres to the spindle fibres at the equator.

spindle-shaped adj. Broadest near the middle and tapering toward both ends, as in some roots. (see fusiform)

spine (L. spina: thorn, prickle) n. A stiff, hard, sharp-pointed plant structure on a plant, arising from below the epidermis, formed by the modification of a plant organ, as a leaf, leaf part, petiole, or stipule. The edge of the holly leaf is drawn out into spines, but in cacti the whole leaf is modified as a spine. Any structure with the appearance of a true spine. Cf. prickle, thorn.

spinescent (L. spinescere: to become covered with spines) adj. Ending in a spine; modified to form a spine; having spines.

sphingophilous adj. Said of entomophilous flowers pollinated by hawk moths, often with a distinctive syndrome (long tube, spreading lobes, whitish color, sweet scent, etc.)

spiniferous (L. spinifer: thorny, prickly) adj. Abounding in or covered with spines; spiny. Also spinose.

spinose (L. spinosus: spine covered) adj. Bearing spines. Also spiniferous, spinous.

spinous See spinose.

spinulate See spinulose.

spinule (L. spinula: small spine) n. A small spine.

spinulose (L. spinula: small spine) adj. Bearing spinules. Also spinulate.

spiny (L. spina: thorn, prickle, spine) adj. With spines

spiracle n. A respiratory aperture, especially any of several tracheal openings in the exoskeleton of an insect or a spider. A small respiratory opening behind the eye of certain fishes, such as sharks, rays, and skates. The blowhole of a cetacean. An aperture or opening through which air is admitted and expelled.

spiral (Gr. speira: spiral) adj. Of leaves or floral organs, borne at different levels on the axis, in an ascending spiral. Cf. cyclic.

spiricle (diminutive of L. spira: spiral, coil) n. A small, coiled thread in the coat of some seeds and achenes which uncoils when moistened.

Spirogyra (Gr. speira: spiral; circle, round) n. A genus of filamentous green algae commonly found in fresh water as skeins of fine green threads. The threads consist of individual cells attached end-to-end. Inside each cell is one or more ribbon-like, spirally arranged chloroplast(s), hence the name Spirogyra. Growth occurs by simple transverse division of cells, and sexual reproduction occurs by fragmentation of threads. Occasionally, Spirogyra undergoes sexual reproduction: two threads lie alongside each other, and the contents of each cell in one strand pass through a temporary tunnel into the corresponding cell of the other strand. The donor thread thus becomes an empty shell, while the recipient thread undergoes a series of changes before resistant spores are released, eventually to produce new threads.

spiromonistichous adj. Said of leaves or floral organs, borne in a single rank in a spiral along the axis.

spongin (L. spongia: sponge) n. Proteinacous compound of which the spicules in Demospongiae (that contains 90% of all sponge species) are composed.

spongiose (L. spongiosus: spongy) adj. Soft and spongy.

spongiostratum n. Spongy hypothallus, usually brown, dark brown-black or black, found in Anzia and Pannoparmelia. Can be continuous or discontinuous.

sponsalia (L. sponsalia: bethrotal) n. See anthesis.

sporadic (Gr. sporadikos: scattered) adj. Occurring in a scattered distribution rather than in a continuous range.

sporangia See sporangium.

sporangial (Gr. spora: seed; aggeion: vase, bowl, container) adj. Related to the sporangium.

sporangiophore (Gr. spora: seed; aggeion: vase, bowl, container; phora: carrying) n. The stalk of a sporangium; the simple or branched stalk that bears one or more sporangia.

sporangium (Gr. spora: seed; aggeion: vase, bowl, container) n. (pl. sporangia) A reproductive structure in plants that produces asexual spores. A megasporangium produces megaspores, which give rise to the female gametophyte; in seed plants it is represented by the ovule. A microsporangium produces microspores, which give rise to the male gametophyte; it is represented in seed plants by the pollen sac. See also sporophyll.

spore (Gr. spora: seed) n. A propagative plant body consisting of a gametophyte enclosed in a non-cellular coat. Spores are enclosed within a capsule (sporangium) and are produced in groups of four (tetrads) when the parent cell divides meiotically. In more primitive plants the spores are identical (isospore) and the condition is called 'homospory'. In more advanced, vascular plants spores of two sizes are produced and the condition is called 'heterospory'. Small, male microspores are contained within a microsporangium; larger, female megaspores within megasporangia. Where spores occur in tetrads the contact surfaces produce a 'trilete' mark on each of the four spores, marking the point for the germination of the prothallus. Less commonly, two contact surfaces are produced, resulting in a 'monolete' marking. Spores which were probably produced singly are 'alete', with no obvious marking. Spores are produced by bacteria, algae, protozoa, fungi, and some plants. They are only just visible to the naked eye, but can be seen as clumps on the underside of fern leaves or under the cap of fungi. Unlike seeds, they contain only a few cells and no embryo, but still grow into new individuals. Most are liberated into the air and travel long distances in air currents, although most algae and some fungi have spores that can swim in water using beating hairs, or flagellae. Other kinds of spores lie dormant where they are produced; dormant spores of bacteria are the longest-surviving living material, resistant to extremes of temperature and drought. Those of the bacterium Bacillus anthracis, which causes anthrax, can survive up to 50 years.

sporeling (Gr. spora: seed) n. All structures developed between the germination of the spore and the formation of the adult gametophore; includes the protonema (variously differentiated) and the juvenile gametophore (in some leafy liverworts characterized by pendulum leaf-segmentation).

sporiferous (Gr. spora: seed; L. ferre: to carry) adj. Bearing spores.

sporocarp (Gr. spora: seed; karpos: fruit) n. A fruiting body containing sporangia. Cf. sporophyte.

sporocyte n. A sporogenous cell; a diploid cell (found in the capsule) that undergoes meiosis to produce spores.

sporogenesis n. Production or formation of spores. Reproduction by means of spores.

sporogenic See sporogenous.

sporogenous (Gr. spora: seed; genna˘: to produce) adj. Of cells or tissues, in which spores are formed. Also sporogenic.

sporogonia See sporogonium.

sporogonium (Gr. spora: seed; gonos: generation) n. (pl. sporogonia) The sporangium of mosses and liverworts.

sporophore (Gr. spora: seed; phora: carrying) n. The aerial spore-producing part of certain fungi; for example, the stalk and cap of a mushroom.

sporophyl See sporophyll.

sporophyll (Gr. sporos, seed; phyllon, leaf) n. A sporangium-bearing leaf often modified in structure. A leaf that bears sporangia (spore-producing structures). In ferns the sporophylls are the normal foliage leaves, but in other plants the sporophylls are modified and arise in specialized structures such as the strobilus (cone) of clubmosses and horsetails and gymnosperms and the flower of angiosperms. Most plants produce spores of two different sizes (small microspores and large megaspores). The sporophylls bearing these are called microsporophylls and megasporophylls respectively. Also sporophyl.

sporophyllary adj. See sporophyll.

sporophyte (Gr. sporos, seed; phyton, plant) n. The generation in the life cycle of a plant that produces spores. The sporophyte is diploid but its spores are haploid. It is either completely or partially dependent on the gametophyte generation in mosses and liverworts, but is the dominant plant in the life cycle of clubmosses, horsetails, ferns, and seed plants. See also alternation of generations. The diploid (2n), spore-producing generation of the plant reproductive cycle, the dominant and conspicuous plant in the vascular plants. Cf. gametophyte.

sporophytic adj. See sporophyte.

sporopollenin n. An organic polymer that makes up the coat of a pollen grain or spore; sporopollenin is extremely resistant to degradation.

Sporozoa (Gr. spora: seed; z˘on: any living being, animal) n. A group of parasitic protozoans that includes Plasmodium, the malaria parasite. Most sporozoans do not have cilia or flagella. Sporozoan life cycles are complex and usually involve both sexual and asexual stages. Some sporozoans are parasites of invertebrates, and the parasites are passed to new hosts by means of spores. Sporozoans that parasitize vertebrates are transmitted from host to host by invertebrates, which act as intermediate hosts. For example, the mosquito Anopheles is the intermediate host of Plasmodium.

sport See bud sport.

spp. Abbreviation for the plural of species.

sprawling adj. Bending or curving downward; lying upon something and being supported by it.

spray n. A slender shoot or branch with its leaves, flowers, or fruits.

spreading adj. Extending nearly to the horizontal; almost prostrate.

sprig n. A small shoot or twig of a plant.

springwood n. Young, usually soft wood that lies directly beneath the bark and develops in early spring, appearing lighter in color than the wood formed later as the growth slows down.

spring wood See springwood.

sprout n. Young plant growth, such as a bud or shoot. The young shoots of plants. A young stemlike growth arising from a plant.

spumose (L. spumosus: foamy) adj. Frothy or foamy. Also spumous.

spumous See spumose.

spur n. A slender, hollow, sac-like or tubelike structure formed by an extension of one or more petals or sepals, i.e. an appendage of a petal or sepal, or of the calyx or corolla, often containing nectar; also refers to a very short branch with closely spaced leaves or flowers and fruits.

spurred adj. Referring to a flower with tubular projections from the petals or sepals, usually with nectar glands; bearing a spur or spurs; calcarate.

squama (L. squama: scale) n. (pl. squamae) A scale, as in some types of pappus in the Compositae (Asteraceae), or such as any of the scales from the cornified layer of the epidermis.

squamaceous (L. squama: scale) See squamate.

squamae See squama.

squamate (L. squama: scale) adj. Scale-shaped. Covered with scales (squamae). Also squamaceous, squamosal, squamose, squamous.

squamella (L. squamula: small scale) n. (pl. squamellae) A small scale or squama.

squamellae See squamella.

squamellate (L. squamula: small scale) adj. With squamellae.

squamiform (L. squama: scale; forma: shape) adj. Scale-like.

squamosal See squamate.

squamose See squamate.

squamous See squamate.

squamulate See squamulose.

squamule (L. squamula: small scale) n. A small, loosely attached thallus lobe of certain lichens. The lodicule of a grass flower.

squamulose (L. squamula: small scale) adj. With minute squamellae; covered with samll scales. Also squamulate.

squarrose (L. squarrosus: buttons covered) adj. With branches spreading and recurved at the ends; abruptly recurved or spreading above the base; rough or scurfy due to the presence of recurved or spreading processes; spreading at right angles with the tips curved downward; branching at right angles, as in rhizines.

squarrulose (diminutive of L. squarrosus: buttons covered) adj. With minute recurved processes.

ssp. Abbreviation for subspecies.

stage n. The major subdivision of a series. A stage is the fourth order unit in chronostratigraphy, the equivalent of age in terms of geologic time units. It refers to the body of rock accumulated during one age unit. When used formally the initial letter of the term is capitalized, e.g. Frasnian Stage. In palaeoclimatology, a climatic, and partly geologic-climatic, term usually defined by a series of sediments or a sequence of fossil assemblages and named at a type locality. For example, the Hoxnian (a temperate stage) is named for organic interglacial deposits at Hoxne, Suffolk, England. The degree of development of a land-form or landscape over time, and which traditionally has been described by the terms 'youthful', 'mature', and 'old age' (see Davisian Cycle). The recognition of such stages implies an orderly evolution and this is now seen as unlikely for many parts of the Earth's land surface.

stalk n. The stem or main axis of a plant, which supports the leaves, flowers, and fruit. Any lengthened support on which an organ grows, as the petiole of a leaf or the peduncle of a flower.

stamen (L. stamen: thread) n. (pl. stamens, stamina) The male reproductive organs in flowers; it is situated immediately within the petals, and is composed, in most cases, of two parts, the filament, and the anther, which is filled with pollen.

staminal (L. stamen, staminis: thread) adj. Of or pertaining to the stamens.

staminal carpellody The transformation of stamens into fleshy carpel-like structures during the early development of the flower, as in papaya.

staminal corona In Apocynaceae-Asclepiadoideae, fleshy outgrowths of tissue, attached abaxially to the staminal column at the bases of the filaments or on the backs of the anthers.

staminate (L. stamen, staminis: thread) adj. With stamens and without pistils, as a male flower which does not produce fruit or seeds; bearing stamens. Cf. pistillate. Also stamineal, staminiferous, staminigerous.

staminate flower Producing or consisting of stamens; of a flower with stamens but no pistils.

stamineal See staminal.

staminiferous (L. stamen, staminis: thread; ferre: to carry) adj. Bearing or having a stamen or stamens. Also staminigerous. See staminate.

staminigerous (L. stamen, staminis: thread; gere: to carry) See staminiferous.

staminode See staminodium.

staminodia See staminodium.

staminodium (Gr. stŕm˘n: thread; eidos: shape, appearance) n. (pl. staminodia) A modified stamen which is sterile, producing no pollen; an organ resembling a stamen. Also staminode.

staminody (Gr. stŕm˘n: thread; eidos: shape, appearance) n. A condition in which other organs, such as petals or sepals, become stamens

staminoid n. A pollenless stamen.

staminophore (Gr. stŕm˘n: thread; phora: carrying) n. A band of tissue around the apex of the hypanthium in a eucalypt flower on which the stamens are inserted.

standard n. The posterior, upper and usually largest petal in the flower in Fabaceae; a vexillium or banner.

stand table See association table.

stapetalum n. Referring to the length of corolla tube with fused or adnate stamens.

starch n. A complex polymer of glucose, used by plants and green algae to store surplus sugar for later use.

starchy adj. Containing starch.

stasis (Gr. stasis: tability, fixedness) n. A period of little or no discernible evolutionary change in a lineage; the 'equilibrium' that alternates with 'punctuations' in the theory of punctuated equilibrium.

staurocytic adj. Said of stomata, with four subsidiary cells each oblique to the long axis of the guard cells.

stegia See stegium.

stegium (Gr. stegŕ: roof) n. (pl. stegia) A covering of thread-like hairs on the styles of some members of the Asclepiadaceae.

stegmata n. SiO2-containing cells usually adjacent to vascular tissue, the wall adjacent to the underlying sclerenchyma, thick, the anticlinal walls thinner, and the outer periclinal wall thinnest; the term is rarely used when the cells are epidermal.

stegocarpous adj. Referring to capsules with a dehiscent operculum. Cf. cleistocarpous.

stele (Gr. stŕlŕ: stele, standing block) n. The central cylinder or cylinders of vascular and related tissue in the stem, root, petiole, leaf, etc., of the higher plants. The vascular tissue (i.e. xylem and phloem) of tracheophyte plants, together with the endodermis and pericycle (when present). The arrangement of stelar tissues is very variable. In roots the stele often forms a solid core, which better enables the root to withstand tension and compression. In stems it is often a hollow cylinder separating the cortex and pith. This arrangement makes the stem more resistant to bending stresses. Monocotyledons and dicotyledons can usually be distinguished by the pattern of their stelar tissue. In monocotyledons the vascular bundles are scattered throughout the stem whereas in dicotyledons (and gymnosperms) they are arranged in a circle around the pith. See actinostele, dictyostele, eustele, haplostele, plectostele, protostele, siphonostele.

stelipilous (L. stella: star; pilus: hair) adj. With stellate hairs.

stellate (L. stella: star) adj. Starlike; said of hairs that branch in such a manner as to radiate from a central point; consisting of star-shaped cells.

stem n. The main ascending axis of a plant typically above the soil surface, having leaves or scales, that develops buds and shoots instead of roots, and with a characteristic arrangement of the vascular tissue. It is developed from the plumule of the embryo.

stem group All the taxa in a clade preceding a major cladogenesis event. They are often difficult to recognize because they may not possess synapomorpies found in the crown group.

stem tuber Swollen structures produced by stolons and runners which remain dormant during adverse conditions and later grow into new plants when the conditions become favorable for growth.

steno- (Gr. stenos: narrow) prefix. Denoting narrowness.

stemonozone n. The tube formed by the adnation of filaments to the corolla, as in Fabaceae-Mimosoideae, essentially an epipetalous androecium when there are numerous stamens.

stenopetalous (Gr. stenos: narrow; petalon: leaf) adj. With narrow petals.

stenophyllous (Gr. stenos: narrow; phyllon, leaf) adj. With narrow leaves.

stenotypic adj. Applied to a taxon with a narrow range of variability. Cf. phenovariant.

Stentor n. A genus of tiny single-celled organisms (see protozoa) occurring in fresh water. Up to 2 mm long, they are trumpet-shaped, with tracts of hairlike cilia over the body surface, and are often attached by a stalk to the substrate. They feed by wafting currents of water containing bacteria, algae, and protozoans into the funnel-shaped gullet entrance. Phylum: Ciliophora.

Stephanian n. The uppermost series in the Silesian (Upper Carboniferous) of Europe, underlain by the Westphalian, dated at 305 to 290 million years ago and roughly contemporaneous with the uppermost Moscovian, Kasimovian, and Gzelian Series. Originally, the lower part of the Stephanian was known as Westphalian E.

steppe n. Grassland; plain; prairie.

stereid n. The slender, elongate, thick-walled, fiber-like cells found in groups (stereid bands) in the costa or stems of some mosses.

stereo- (Gr. stereos: solid) prefix. Having three dimensions.

stereom See stereome.

stereome n. A collective term for all the supporting tissues in the vascular tissue of a plant. Also stereom.

stereomorphic (Gr. stereos: solid; morphŕ: shape) adj. Radially symmetrical, so that a line drawn through the middle of the structure along any plane will produce a mirror image on either side; essentially the same as actinomorphic.

stereospecific reaction A reaction that results predominantly in only one of a variety of possible stereoisomers (e.g. inversion of configuration).

sterigma n. (pl. sterigmata) The persistent leaf base of the leaves of some coniferous trees. A small spore-bearing stalk found in certain fungi; in the Basidiomycota, sterigmata develop as outgrowths of a basidium, each bearing a basidiospore at its tip.

sterigmata See sterigma.

sterile (L. sterilis: infertile) adj. Infertile, as a stamen that does not bear pollen, or a flower that does not bear seed.

steroid See steroids.

steroidal adj. Relating to or characteristic of steroids or steroid hormones.

steroids n. A class of organic chemical compounds with a basic structure of three six-membered carbon rings joined to a five-membered ring. Steroids and their hydroxy derivatives (sterols) fulfil many biological roles in plants and animals and include the sex hormones, corticosteroids, bile acids, vitamin D, and moulting hormones in insects. Cholesterol is an important precursor in the synthesis of many steroids.

sterome n. The entire system of stereids in a moss plants.

stichic adj. Said of the horizontal orientation of the spindle of nuclei in the basidium.

stichidia See stichidium.

stichidium n. (pl. stichidia) A special podlike or fusiform branch containing tetraspores. It is found in certain red algŠ.

stigma (L. stigma: mark) n. The upper tip or part of the pistil of a flower receiving the pollen. It is generally situated at the upper extremity of the style and is usually sticky. In insect-pollinated plants the stigmas are held within the flower, whereas in wind-pollinated species they hang outside it.

stigmatic (L. stigma, stigmatis: mark) adj. Belonging to or characteristic of the stigma. Pertaining to the stigma.

stigmatiferous (L. stigma, stigmatis: mark; ferre: to carry) adj. Bearing a stigma

stigmatose (L. stigma, stigmatis: mark) adj. With conspicuous stamens

stilt roots Adventitious support roots, as in the yellow birch (Betula alleghaniensis).

stilt-roots See stilt roots

stipe (L. stipes: post, trunk) n. A stalk supporting a structure, as the stalk attaching the ovary to the receptacle in some flowers; the stalk-like support of a pistil; the stalk-like basal part of an ovary, or of a fruit such as an achene; the stem bearing pileus in mushrooms and toadstools; in ferns, the petiole of a frond; in algae, the cylindrical basal portion of a thallus; the unbranched basal part of an erect stem in a dendroid or frondose moss (Pterobryaceae) and some anacrogynous liverworts (Symphyogyna).

stipel (L. stipula: stalk, straw, culm, stubble) n. A small secondary stipule at the base of a leaflet.

stipellate (L. stipula: stalk, straw, culm, stubble) adj. Bearing stipels.

stipitate (L. stipes, stipitis: trunk, post) adj. Stalked; borne on a stipe; having or supported by a stipe of an ovary, borne on a gynophore.

stipitate-glandular (L. stipes, stipitis: trunk, post; glandula: gland) adj. Bearing stalked glands.

stipitiform (L. stipes, stipitis: trunk, post; forma: shape) adj. With the form of a stipe.

stipular (L. stipula: stalk, straw) adj. Of or pertaining to a stipule.

stipulate (L. stipula: stalk, straw) adj. Bearing stipules. Also stipulose

stipule (L. stipula: stalk, straw) n. One of two foliaceous or membranaceous processes developed at base of a leaf petiole, in many dicotyledons, (one on each side as in roses), sometimes in tendril or spine form, sometimes fused. Syn. paraphyllum.

stipuliform (L. stipula: stalk, straw; froma: shape) adj. Stipule-shaped.

stipulose See stipulate.

stolon (L. stolo, stolonis: shoot) n. A long aerial side stem that gives rise to a new daughter plant when the bud at its apex touches the soil. Plants that multiply in this way include blackberry and currant bushes. Gardeners often pin down stolons to the soil to aid the propagation of such plants. This process is termed layering.

stolonate (L. stolo, stolonis: shoot) adj. Having stolons, developping from a stolon.

stoloniferous (L. stolo, stolonis: shoot; ferre: to carry) adj. Producing or bearing stolons.

stoloniform adj. Refers to stoloniferous branches or stems.

stolonization (L. stolo, stolonis: shoot) n. The production of stolons.

stoma (Gr. stoma, stomatos: mouth) n. (pl. stomas, stomata). A pore, large numbers of which are present in the epidermis of leaves (especially on the undersurface) and young shoots. The stomata function in gas exchange between the plant and the atmosphere. Each stoma is bordered by two semicircular guard cells (specialized epidermal cells), whose movements (due to changes in water content) control the size of the aperture. The term stoma is also used to mean both the pore and its associated guard cells. (The Funariaceae have single guard cell with an opening in the center). Also stomata, stomate.

stomachic adj., n. Of or relating to the stomach; gastric. Beneficial to or stimulating digestion in the stomach. An agent, such as a medicine, that strengthens or stimulates the stomach.

stomachically adv. See stomachic.

stomata See stoma.

stomatal (Gr. stoma, stomatos: mouth) adj. Of, pertaining to, or of the nature of a stoma; having stomata. Also stomatiferous, stomatic. Syn. stomatous.

stomate See stoma.

stomatic See stomatal.

stomatiferous (Gr. stoma, stomatos: mouth; L. ferre: to carry) adj. Bearing stomata.

stomatous See stomatal.

stomia See stomium.

stomium (Gr. stomion: opening) n. (pl. stomia) A region of dehiscence, e.g. of an anther in flowering plants or of a capsule in mosses. A region of thin-walled cells in certain spore-producing structures that ruptures to release the spores. For example, in the sporangium of the fern Dryopteris the stomium ruptures when the annulus dries out.

stone n. The hard, woody endocarp enclosing the seed of a drupe.

stone fruit A drupe; a fruit with a stony pit.

stone cells The brachysclereidal cells that can make the flesh of pears, etc., gritty.

stool n. The base of plants which produce new stems each year; a group of stems arising from a single root

storied adj. Said of vascular cambia, when the fusiform initials are arranged in horizontal tiers in tangential section.

strain n. A number of plants which have similar characteristics such as color blends, different enough to be designated, but not sufficiently distinct to be considered as a horticultural variety. A term incorrectly applied to selections of cultivars (varieties); designation of a selection of a cultivar as a strain or equivalent term is not permitted under the International Code of Nomenclature of Cultivated Plants; any selection that shows sufficient variation from the parent cultivar to render it worthy of a name is to be regarded as a distinct cultivar; use of the term for a cultivar of hybrid origin, e.g., Lilium Olympic strain, is not recommended; such assemblages are more correctly termed `group'. Note that the Guidelines for Classifying Cultivated Plant Populations (1978) stipulate that variety and cultivar are considered exact equivalents.

stramineous (L. stramineus: made of straw) adj. Straw-like in color or texture. Also stramineus.

stramineus See stramineous.

strap n. The ligule of a ray flower in the Compositae (Asteraceae).

strap-shaped adj. Elongated and flat.

stratification (L. stratus: spreading, lying flat) n. The process of refrigerating seeds to imitate natural wintering as an aid to germination.

stratified adj. Said of phloem, with periclinally-running bands of fibers interspersed with the conducting tissue.

stratigraphic nomenclature The naming of stratigraphic and geologic-time units according to established practices and principles. Formal naming of a stratigraphic unit occurs when the unit is first proposed and described from a type section (see Stratotype), which acts thereafter as the standard reference for that unit. Ideally, the name given is binomial, and in the case of chronostratigraphic and lithostratigraphic units consists of a preceding geographic name taken from the type locality (plus lithological description where appropriate), followed by the name of the unit, e.g. Ludlow Series and Elk Point Group. The names of biostratigraphic units consist of the name of the characteristic fossil plus the relevant unit term, e.g. Monograptus uniformis Range zone. The name chosen for a stratigraphic unit should be unique to that unit. When used as a proper name, as above, the initial letters are capitalized. Except in very special circumstances the first formal name given has priority and is adhered to. In practice many well-known units, e.g. Coal Measures, Millstone Grit, were named long before the present conventions were established, and to avoid confusion these names are preserved in their original form. Geologic-time units generally take the ir preceding name from that of the corresponding chronostratigraphic unit, plus the name of the unit (period, epoch, age, etc.), e.g. the Jurassic Period, from the Jurassic System (named after the type area in the Jura Mountains). The names of eons and eras (e.g. Phanerozoic Eon, Mesozoic Era) were proposed independently, so that the names for the corresponding eonothems and erathems are derived from the time units.

stratose adj. In ayers, i.e. unistratose, bistratose, multistratose. Cf. seriate.

streptocarpous (Gr. streptos: breaded, twisted; karpos: fruit) adj. With twisted fruits

streptophytes (Gr. streptos: breaded, twisted; phyton: plant) n. The clade consisting of the plants plus their closest relatives, the charophytes.

stria (L. stria: furrow, striation) n (pl. striae) A fine line or groove, a slight ridge or furrow.

striae See stria.

striate (L. striatus: fluted, streaked, grooved) adj. Striped with fine, parallel longitudinal lines or ridges; e.g. Vaccinium angustifolium. Also striated.

striated See striate.

striation (L. stria: furrow, striation) n. Striated condition or appearance; a Sstria; one of many parallel striae.

strict (L. strictus: tight, narrow, rigorous) adj. Very straight and upright, not at all spreading.

strict consensus A method for choosing among several most parsimonious trees generated by a phylogenetic analysis; strict consensus means that only clades that show up in all the most parsimonious trees are recognized.

stricture n. Abnormal narrowing of a passage, especially the urethra, oesophagus or intestine

striga (L. striga: row of stacks, stack [of hay]) n. A bristle; a straight, stiff, sharp, appressed hair.

strigillose (diminutive of L. striga: row of stacks, stack [of hay]) adj. Minutely strigose. Also strigulose.

strigose (L. striga: row of stacks, stack [of hay]) adj. Covered with stiff hairs; ridged; marked by small furrows; of a surface clothed with stiff, often appressed hairs, these usually pointing in one direction.

strigulose See strigillose

striolate adj. Finely ridged.

strobilaceous (Gr. strobilion: small pine cone) adj. Ressembling a strobile; conelike. Also strobiline, strobiliform, strobiloid.

strobile See strobilus.

strobili See strobilus.

strobiliform See strobilaceous.

strobiline adj. Of or pertaining to a strobile. Also strobilaceous, strobiliform.

strobiloid See strobilaceous.

strobilus (Gr. strobilion: small pine cone) n. (pl. strobili) A type of composite fruit that is formed from a complete inflorescence. It produces achenes enclosed in bracts and when mature becomes cone-shaped. The hop fruit is an example. A 'cone' consisting of sporophylls borne close together on an axis, i.e. a tightly clustered group of sporophylls arranged on a central stalk. A woody cone, as in Gymnospermae. Also strobile.

stroma (Gr. str˘ma, str˘matos: what one spreads, cover, tablecloth) n. (pl. stromata) In certain fungi, a compact, somatic mass of fungous tissue, in or on which the fructifications may develop. A mass or matrix of vegetative hyphae (usually black) with or without tissue of the host or substrate, sometimes Sclerotium-like in form, in or on which spores are produced, often covering a group of several ascocarps.

stromata See stroma.

strombuliform (L. strombos: spiraling object; forma: shape) adj. Shaped like a strombus, like a twisted, conical seashell.

strombus (Gr. strombos: spiraling object) n. A legume which is spirally coiled, as in Medicago.

strophiolate (L. strophiolum: ribbon) adj. Furnished with a strophiole, or caruncle, or that which resembles it. Also strophiolated.

strophiolated See strophiolate.

strophiole (L. strophiolum: ribbon) n. A crestlike excrescence about the hilum of certain seeds; a caruncle. See caruncle.

struma (L. struma: scrofulous tumor) n. (pl. strumae) A cushion-like swelling on an organ, as that at one side of the base of the capsule in many mosses.

strumae See struma.

strumose (L. strumosus: scrofulous) adj. With a covering of cushion-like, goiter-like swelling swellings; bullate.

strumulose adj. With a small swelling.

sty n. Inflammation of one or more sebaceous glands of an eyelid.

stylar (Gr. stylos: column, pillar) adj. Of or pertaining to a style.

stylate ad. Having a style or styles.

style (Gr. stylos: column, pillar) n. Slender upper part of pistil (carpel), supporting stigma, located above the ovary, and connecting the stigma to the ovary. In many plants it is elongated to aid pollination.

stylocarpellous (Gr. stylos: column, pillar; karpos: fruit) adj. With a style, but without a stipe, i.e. the normal carpel. Cf. astylocarpellous, astylocarpepodic and stylocarpepodic.

stylocarpepodic (Gr. stylos: column, pillar; karpos: fruit; pous, podos: foot) adj. With a style and a stipe. Cf. astylocarpepodic, astylocarpellous, stylocarpellous.

stylodia See stylodium.

stylodious See unicarpellous.

stylodium (Gr. stylos: column, pillar) n. (pl. stylodia) A stigma branch, as in some members of the Geraniaceae. A long, filiform style as in Lilaea.

stylopod See stylopodium.

stylopodia See stylopodium.

stylopodic (Gr. stylos: column, pillar; pous, podos: foot) adj. With a stylopodium

stylopodium (Gr. stylos: column, pillar; pous, podos: foot) n. (pl. stylopodia) The fleshy support at the base of the style in flowers of the carrot family, the Apiaceae (Umbelliferae).

stylulus n. An elongated part of an individual free carpel down which pollen tubes travel to that carpel alone.

stylus n. (pl. styli) A column; a one-celled, uniseriate or multiseriate, subulate to triangular structure found between the lobule and the stem in certain leafy liverworts; an archaic term for the archegonial neck.

styptic (Gr. styptikos: astringent) adj., n. Contracting the tissues or blood vessels; astringent. Tending to check bleeding by contracting the tissues or blood vessels; hemostatic. A styptic drug or substance.

suaveolent (L. suaveolens: with a sweet odor) adj. Fragrant.

sub- (L. sub: under) prefix. Meaning under, slightly, somewhat, or almost.

sub-opposite See subopposite.

sub-sessile See subsessile.

subacute (L. sub: under; acutus: pointed, sharp) adj. Slightly acute.

subalpine (L. sub: under; Alpinus: alpine) adj. Growing in the mountains below the alpine zone and above the montane zone.

subapical (L. sub: under; apex, apicis: tip, summit) adj. Near the apex.

subarctic adj. Of or relating to latitudes immediately south of the Arctic Circle.

subbasal (L. sub: under; basis: base) adj. Near the base.

subcapitate (L. sub: under; caput, capitis: head) adj. Almost capitate.

subcordate (L. sub: under; cor, cordis: heart) adj. Almost cordate.

subcorymbose (L. sub: under; Gr. korymbos: flower cluster) adj. Almost corymbose.

subcylindric (L. sub: under; cylindrus: cylinder) adj. Almost cylindric in shape.

subentire (L. sub: under) adj. Almost entire.

subepilithic adj. Said of a crustose thallus, intermediate between endolithic and epilithic.

suber (L. suber: cork) n. Cork.

suberic (L. suber, suberis: cork) adj. Of or pertaining to cork.

suberine (L. suber, suberis: cork) n. A waxlike, fatty substance, occuring in cork cell walls and in or between other cells, that on alkaline hydrolysis yields chiefly suberic acid.

suberization (L. suber, suberis: cork) n. The impregnation of cell walls with suberin causing the formation of cork.

suberose (L. subereus: corky) adj. Corky in texture; of the nature of cork, corklike. Also suberous.

suberous adj. See suberose.

subfamily n. A taxonomic category of related organisms ranking between a family and a genus.

subfoliaceous (L. sub: under; foliaceus: in the shape of a leaf) adj. Almost foliaceous.

subgenera See subgenus.

subgenus n. (pl. subgenera) A taxonomic group that is a subdivision of a genus but of higher rank than a species.

subglabrate (L. sub: under; glaber, glabra: without hair) adj. Almost glabrate.

subglobose adj. Inflated but not so much as to be round or globose.

sublageniform adj. Said of conidia, short and rod-shaped with a swelling at one end, giving the conidium a ▒elongated, flask-shaped appearance.

sublignous (L. sub: under; ligneus: woody) adj. Almost woody.

submergence n. A change in the relative levels of water and land either from a sinking of the land or a rise of the water level.

submersed (L. submersus: submerged, engulfed) adj. Submerged; growing under water.

submersed plants Plants growing with their root, stems, and leaves completely under the surface of the water.

submuriform Said of ascospores, having both transverse and longitudinal septa, but in which not more than 15 cells may be seen. Cf. muriform.

subopposite adj. Almost opposite but one leaf or leaflet of each pair a little above the other.

suborbicular (L. sub: under, below; orbis: circle) adj. Approximately circular.

subrhizomatous (L. sub: under; Gr. riza: root) adj. Almost rhizomatous.

subscapose (L. sub: under; scapus: stalk [of a plant]) adj. Almost scapose

subsessile (L. sub: under; sessilis: on what one can sit, sessile)) adj. With a slightshort stalk.

subshrub (L. sub: under) n. A suffrutescent perennial plant; a small shrub.

subsidiary cells Epidermal cells that are clearly differentiated from the others and that immediately surround the guard cells of the stomata, q.v. for the various distinctive arrangements of these cells.

subsorediate adj. With granules (as in soredia), but which are partly corticate.

subspecies (L. sub: under; species: species, type)) n. A taxonomic category applied to specimens which form a distinct group within a species, but are not different enough to be classed as a species in their own right.

subspicate (L. sub: under; spicatus: furnished with spikes) adj. Almost spicate, but with short pedicels on some or all of the flowers or florets.

substereid adj. Almost with the characteristics of a stereid, but with walls not as strongly thickened.

subsume v. To classify, include, or incorporate in a more comprehensive category or under a general principle.

subtend (L. subtendere: to tighten below, to stretch out below) v. To be below and close to, as a bract may subtend an inflorescence.

subterranean (L. subterraneus: underground) adj. Below the surface of the ground. Also subterraneous.

subterraneous See subterranean.

substratum n. The underlying layer, or base to which a lichen is fixed.

subtribe n. A subdivision of a tribe.

subtropical (L. sub: under; tropicus: tropical) adj. Distributed in areas intermediate between tropical and temperate regions; nearly tropical.

subula (L. subula: awl) n. A fine, lomg, sharp, slender point.

subulate (L. subula: awl) adj. Awl-shaped; slender and tapering gradually to a fine point.

subumbellate adj. See sub- and umbellate.

successional species A species of that replaces a more shade-intolerant pioneer or other successional species in a forest. The seedlings of a successional species can grow in the shaded understory and mature. The process of succession continues until the most shade-tolerant species (or climax species) is established.

succubous (L. succubare: to lie under) adj. Of leaves overlapping with the base of each leaf covering part of that under it. Cf. incubous.

succulent (L. succus: sap) n. A plant that conserves water by storing it in fleshy leaves or stems. Succulents are found either in dry regions or in areas where there is sufficient water but it is not easily obtained, as in salt marshes. Such plants are often modified to reduce water loss by transpiration. For example, the leaves of cacti are reduced to spines.

sucker n. A shoot from the root or lower part of a stem. In roses, a young cane emerging below the bud union and therefore representing the variety of the understock rather than the top variety. A shoot appearing on a tree limb is called a water sprout. v. intr. To send out suckers or shoots.

suckering See sucker.

sucrose n. A common disaccharide made up of glucose and fructose.

sudorific adj., n. Causing or increasing sweat. A sudorific medicine.

suffrutescent (L. sub: under; frutex, fruticis: shrub) adj. Somewhat shrubby; slightly woody at the base.

suffrutex n. Low-growing woody shrub or perennial with woody base; subshrub.

suffruticose (L. sub: under; fruticosus: full of shrubs) adj. Somewhat woody

suffruticulose adj. (diminutive of L. sub, under; fruticosus: full of shrubs) Moderately frutescent; obscurely shrubby; usually woody only basally.

suffused (L. suffusus: bathed, penetrated) adj. Tinted or tinged.

sugar n. Any of several small carbohydrates, such as glucose, which are 'sweet' to the taste.

sulcate (L. sulcus: furrow) adj. Furrowed, grooved; scored with deep, parallel furrows or grooves, as horsetail stems; of pollen grains with elongate apertures. Also sulcated. Cf. colpate, colporate, porate, pororate, ulcerate; costate, striate.

sulcated See sulcate.

sulci See sulcus.

sulcus (L. sulcus: furrow) n. (pl. sulci) A groove or furrow.

sulfide n. A compound of bivalent sulfur with an electropositive element or group, especially a binary compound of sulfur with a metal.

sulfoxide n. Any of various organic compounds that contain a sulfinyl group.

sulfureous (L. sulfureus: of sulfur) adj. Sulfur-colored.

summer annual A plant with seeds germinating in spring or early summer and completing flowering and fruiting in late summer or early fall and then dying.

summerwood n. Wood that is produced during the latter part of the growing season and is harder and less porous than springwood.

summer wood See summerwood.

superaxillary (L. super: above; axilla: armpit) adj. Attached above the axil.

superior (L. superior: higher, more above) adj. Describing a structure that is positioned above or higher than another structure in the body. For example, in flowering plants the ovary is described as superior when located above the other organs of the flower (see hypogyny). Cf. inferior.

superior ovary One that is located above the perianth and free of it.

supervolute adj. Said of leaf ptyxis, very strongly curved adaxially, the margins overlapping.

supervolute-curved adj. Said of leaf ptyxis, very strongly curved adaxially, but the edges not overlapping.

supervolute-involute adj. Said of leaf ptyxis, strongly curved adaxially, but the very margins each strongly incurved, so not overlapping.

supine (L. bent backward, turned back) adj. Lying on the back or with the face upward.

supra-axillary (L. supra: above; axilla: armpit) adj. Borne above the axil.

supraligular (L. supra: above; ligula: little tongue) adj. Attached above the ligule.

surculi See surculus.

surculose (L. surculus: layer, runner, shoot) adj. Producing suckers or runners from the base or from rootstocks.

surculose-proliferous (L. surculus: runner, shoot; L. proles, prolis: offspring; ferre: to bear) adj. Reproducing by suckers or runners.

surculum (L. surculus: layer, runner, shoot) n. A fern rhizome.

surculus n. (pl. surculi) A leafy upright shoot from a rhizome.

surcurrent adj. Extending upward from the point of insertion, as a leaf base that extends up along the stem. Cf. decurrent.

surficial adj. Growing near the ground, or spread over the surface of the ground.

suspensor (L. uspended) n. A filament by which the embryo is suspended in some seeds.

suture (L. sutura: seem, suture) n. A seam formed when two parts unite; a seam or line or groove; usually applied to the line along which a fruit dehisces; any lengthwise groove that forms a junction between two parts.

swale n. A depression or shallow hollow in the ground, typically moist.

swamp n. A seasonally flooded bottomland with more woody plants than a marsh and better drainage than a bog. A lowland region saturated with water.

syconia See syconium.

syconium (Gr. sykon: fig) n. (pl. syconia). A type of composite fruit formed from a hollow fleshy inflorescence stalk inside which tiny flowers develop. Small drupes, the 'pips', are produced by the female flowers. An example is the fig. Also syconus.

syconus See syconium.

syllepsis n. The timing of axillary growth, development of an axillary bud from primordium to mature branch structure that is to all intents and purposes uninterrupted.

sylvan adj. Of or pertaining to a sylva; forestlike; hence, rural; rustic. Abounding in forests or in trees; woody.

sylvicolous adj. Dwelling in forests.

sym- (Gr. syn: together, with) prefix. Meaning united.

symbiont (Gr. symbios, symbion: that lives with) n. An organism living in symbiosis; especially: the smaller member of a symbiotic pair.

symbiosis (Gr. symbios, symbion: that lives with) n. An interaction between individuals of different species (symbionts). The term symbiosis is usually restricted to interactions in which both species benefit (see cooperation; mutualism), but it may be used for other close associations, such as commensalism, inquilinism, and parasitism. Many symbioses are obligatory (i.e. the participants cannot survive without the interaction); for example, a lichen is an obligatory symbiotic relationship between an alga or a blue-green bacterium and a fungus.

symbiotic adj. Of, resembling, or relating to symbiosis.

symmetric (L. symmetria: symmetry) adj. Said of a flower having the same number of parts in each floral whorl.

sympatric (Gr. syn: together, with; patra; fatherland) adj. Describing groups of similar organisms that, although in close proximity and theoretically capable of interbreeding, do not interbreed because of differences in behaviour, flowering time, etc. Cf. allopatric.

sympatry n. One of four theoretical models for the phenomenon of speciation. Sympatric speciation is the genetic divergence of multiple populations (from a single parent species) inhabiting the same geographic region; such that those populations become different species.

sympetalous (Gr. syn: together, with; petalon: leaf) adj. With the petals united, at least near the base. Syn. gamopetalous; Cf. apopetalous and polypetalous.

sympetaly (Gr. syn: together, with; petalon: leaf) n. Property of plants having the petals united, at least near the base. See sympetalous.

symplesiomorphic adj. With a shared primitive trait (plesiomorphy).

symplesiomorphy n. Shared primitive trait.

sympodia See sympodium.

sympodial (Gr. syn: with, together; pous, podos: foot) adj. Of growth, without a single, persistent growing point. A specialized growth pattern, season after season, in which the terminal bud dies, or blows in an inflorescence, with growth continuing by development of an axillary bud instead of the terminal bud. A growth pattern in which the primary axis is superseded by a succession of secondary axes; in liverworts, the new primary axis is derived from one fork of a dichotomous or pseudodichotomous branch that overtops the other. Cf. monopodial, dichotomous.

sympodially adv See sympodial.

sympodium n. (pl. sympodia) A main axis appearing to be simple, but actually consisting of a number of short axillary branches rather than a continuation of the main axis; after each season's growth the shoot tip of the main stem stops growing (sometimes terminating in a flower spike); growth is continued by the tip of one or more of the lateral buds. Cf. monopodium.

syn- (Gr. syn: together, with) prefix. Meaning united

synanamorph n. Two or more anamorphs of the same teleomorph.

synandria See synandrium..

synandrium (Gr. syn: together, with; anŕr, andros: male) n. (pl. synandria) An androecium with the anthers of the stamens cohering. Cf. syngenesious.

synandrous (Gr. syn: together, with; anŕr, andros: male) adj. With united anthers. Also synantherous.

synangia See synangium.

synangium (Gr. syn: together, with; aggeion: bowl)) n. (pl. synangia) Of fruit, several fruits united in a single structure. A cluster of sporangia which have become fused in development.

synantherous (Gr. syn: together, with; anthŕros; flowered) See synandrous.

synanthesis (Gr. syn: together, with; anthŕsis: flowering) n. The male and female parts of a flower maturing simultaneously. Cf. protandry and protogyny.

synanthious See synanthous.

synanthous (Gr. syn: together, with; anthos: flower) adj. With leaves appearing simultaneously with the flowers. also synanthious.

synanthy (Gr. syn: together, with; anthos: flower) n. The abnormal fusion of two or more flowers.

synapomorphic adj. Said of a character, derived, shared by two or more taxa for which the synapomorphic character indicates their common ancestry. See synapomorphy.

synapomorphy (Gr. syn: together, with; apo: away; morphŕ: shape) n. The possession of apomorphic features by two or more taxa in common (i.e. the features are shared, derived). If the two groups share a character state that is not the primitive one, it is plausible that they are related evolutionarily, and only synapomorphic character states can be used as evidence that taxa are related. Phylogenetic trees are built by discovering groups united by synapomorphies.

synapses See synapsis.

synapsis (Gr. synaptos: linked, joined, united) n. (pl. synapses) The close association between homologous chromosomes that develops during the first prophase of meiosis. The two chromosomes move together and an exact pairing of corresponding points along their lengths occurs as they lie side by side. The resulting structure is called a bivalent. Syn. pairing.

synaptic (Gr. synaptos: linked, joined, united) adj. See synapsis.

synaptically adv. See synapsis.

syncarp (Gr. syn: with, together; karpos, fruit) n. A multiple or aggregate fruit derived from numerous separate ovaries of a single flower; a collective unit, as a blackberry. An intermediate stage of apocarp and paracarp, the contact zones fusing, forming septa, but leaving the individual carpels unchanged (axile placentation).

syncarpous (Gr. syn: with, together; karpos, fruit) adj. Of a flower, having two or more carpels, all fused together, united in a compound ovary; e.g. the gynoecium of Vaccinium angustifolium. Cf. apocarpous.

syncarpy (Gr. syn: with, together; karpos, fruit) n. The condition in which the female reproductive organs (carpels) of a flower are joined to each other. It occurs, for example, in the primrose. Cf. apocarpy.

syncorticate adj. Covered by upper cortex; said of apices of isidia, entire, and shiny or blackened.

syncytia See syncytium.

syncytium n. (pl. syncytium) A cell containing several nuclei.

synergid See synergids.

synergids (Gr. synergos: that gives help, that does the same work) n. The two nuclei in the embryo sac of flowering plants that are closely associated with the oosphere, or egg cell, to form the egg apparatus.

synflorescence n. A compound inflorescence composed of both terminal and lateral flowering branches, an indeterminate inflorescence.

syngamic adj. See syngamy.

syngamous adj. See syngamy.

syngamy (Gr. syn: together, with; gamos: marriage) n. Union of gametes, as in fertilization or conjugation; sexual reproduction. See fertilization.

syngenesia n. Plants with the anthers fused, forming a ring around the style, e.g. Asteraceae (Compositae). A LinnŠan class of plants in which the stamens are united by the anthers.

syngenesian adj. Having the stamens united by the anthers; of or pertaining to the Syngenesia. Also syngenesious.

syngenesious (Gr. syn: together, with; genesis: production) adj. Of the stamens of one flower fused together by the anthers, e.g. in Asteraceae. Cf. synandrium.

synnema (Gr. syn: together, with; nŕma: thread) n. The column composed of united filaments in a flower with monadelphous stamens.

synoecia See synoecium.

synoecious (Gr. syn: together, with; oikos: house) adj. With staminate and pistillate flowers together in the same head. In mosses, having antheridia and archegonia on the same receptacle.

synoecium n. (pl. synoecia) Archegonia, antheridia and surrounding bracts (perigonium or involucre).

synoicous adj. With antheridia and archegonia mixed in the same gametoecium.

synorganization n. The very close connection of organs of the same or different kinds to form a functional structure, usually involving some fusion of the parts involved.

synsepalous (Gr. syn: together, with; skepas: covering, shelter; [pe]talon: leaf) adj. Gamosepalous; with sepals joined at their margins

syntepalous (Gr. syn: together, with) adj. Said of flowers in which the tepals are fused.

syntepalum n. A cup or tube made up of two or more united sepals; a fused calyx. In Musaceae, a unilaterally split tube formed by the coherence of 3 sepals and 2 anterior petals in flowers of some species.

synthesis table See association table.

synthetic variety A variety produced by crossing inter se a number of genotypes selected for good combining ability in all possible hybrid combinations, with subsequent maintenance of the variety by open pollination.

syntropous adj. Said of the curvature of an ovule with respect to the carpel margin that bears it, curvature in the same direction to the curvature of the margin.

syntype (Gr. syn: together, with; typos: mark, image) n. One of two or more specimens cited by the author at the time of publication of a name for which no holotype was designated. All specimens in a type series in which no holotype was designated.

synzoochory (Gr. syn: together, with; z˘on: animal; kh˘re˘: to move) n. Dispersal of seed by animals, e.g. nuts buried and forgotten by small animals, seeds with an elaoiosome (oily outgrowth), e.g. Trillium, Viola, carried by ants and dropped en route, etc.

syphilis n. A contagious venereal disease caused by Treponema pallidum and usually transmitted by direct contact. Oral lesions include primary chancre, secondary mucous patches and split papule, and tertiary gumma.

syphilitic adj.; n. Of, relating to, or affected with syphilis. A person affected with syphilis.

system (Gr. systŕma: union of various objects or of the parts of a same object) n. The chronostratigraphic equivalent of the time unit period. Systems are subdivided into series, and together several systems constitute an 'erathem'. When used formally the initial letter of the term is capitalized, e.g. the Devonian System.

systematics (Gr. systŕmatikos: that forms a whole, that rests on a body of principles) n. Field of biology that deals with the diversity of life. Systematics is usually divided into the two areas of phylogenetics and taxonomy.

systylius adj. With an operculum remaining attached to the tip of the columella after dehiscence; e.g. Hymenostylium. Also systylous.

systylous See systylius.