The Asteraceae family
The words or terms in red
(actually dark orange) in the text are defined in a
The Asteraceae, a taxon of
flowering plants, is the
second largest family in the
with some 1,100 genera
and over 20,000 recognized
with around 350 genera and 2687 species in the U.S. and Canada, and,
from the Flore Laurentienne Frère Marie Victorin,
41 genera and 311 species in Québec.
Only the orchid family (Orchidaceae) is larger,
with about 25,000 described species.
The Asteraceae are herbs,
or less commonly trees.
They show remarkable variation in growth form and general
because they occur in so many different localities and habitats.
The most common characteristic of all these plants, is that what is usually
called a flower, is an inflorescence
or flower head,
a densely packed cluster of many small, individual flowers, usually called
florets (meaning small flowers).
The uniqueness of the Asteraceae family is that what first seems to be
a single large flower is actually a composite of many smaller flowers.
If one looks closely at a Black-eyed Susan (Rudbeckia hirta) in bloom,
one can see that there are hundreds of little flowers growing on a disk,
the inner portion of the flower head,
the brown center of the Rudbeckia, each producing just one seed.
Each 'disk flower' has 5 tiny petals fused together, plus 5
around a pistil
with antennae-like stigmas.
The outer perimeter of a flower head, the yellow 'petals' of the
Rudbeckia, is composed of
the 'ray florets' or ray flowers,
each flower with its petals fused together;
each ray flower is also termed a ligule.
The three types of flower head
Ray florets only
Disk florets only
Disk and ray florets
(You can click the thumbnails above to get a larger view).
The Asteraceae were (and still are) also known as the Compositae.
The alternative family name is derived from the Latin word
compositus which means, in one of it many meanings,
properly disposed, properly arranged.
This refers to the collection of different florets
arranged together in the inflorescence.
For family names, the modern tendency in taxonomy is to use the
name of a familiar plant in a certain family and to add the suffix -aceae
to the name. In this way the family name Asteraceae is made up by using
the name Aster and adding -aceae.
However, the long prevailing name
Compositae is also authorized as an alternative family name.
Technically then, a species of the Asteraceae family is
characterized by having the flowers reduced and organized into
an involucrate pseudanthium
in the form of a head or
The flowers that compose the inflorescence of an Asteraceae
are of two basic types:
and both types of flowers can often be found within the same head, with
the central flowers being tubular as in the Rudbeckia hirta.
If the head has only 'disk flowers' and lacks 'ray flowers'
it is said to be
The so-called disciform heads
have bisexual central disk flowers
surrounded by female flowers that have a very slender tube
and an extremely suppressed or obsolete ligule.
If the head has only 'ray flowers" and lacks 'disk flowers' it is said to be
it consists then of bisexual florets, with generally 5 rather
than 3 distal teeth.
- those with tubular
actinomorphic sympetalous corollas
mostly with 3 or 5 lobes,
the 'disk flowers', the florets of the
brown center of the Rudbeckia hirta or the florets of the
Matricaria matricarioides above;
- those with strap-shaped or
radiate zygomorphic corollas,
the 'ray flowers', in common parlance, the blue 'petals' of the
Cichorium intybus or the yellow 'petals' of the
Rudbeckia hirta above.
Depending on the species, either type of flower may be
Where both types of flowers are found in a single head,
the central flowers have
usually with 4 times lobed
or 5 times lobed corollas,
and are generally bisexual,
while the peripheral flowers have strap-shaped corollas
generally with 3 distal teeth,
but at times 2 or 5 teeth,
and are usually female.
The head (capitulum)
is then an inflorescence and a number of
capitula are often
aggregated together to form a secondary inflorescence or
The capitulum is surrounded on the outside by one or several layers
of involucral bracts resembling the
calyx of other flowers.
In all cases then the flowers do not have a
or it so highly modified as
on the ovary summit
that it is given the alternative name of
The pappus is an adaptation for wind dispersal
of the fruit. Sometimes the pappus contains hooks, which help with animal
dispersal of the fruit.
In some Asteraceae the pappus is absent, in which case
the fruits often have wings, which help with wind
The bracts are mostly green (herbaceous)
but can also be brightly colored
like in Everlastings
or they can have a thin, dry, membranous
The involucral bracts are mostly free and arranged in
rows, overlapping like the tiles of a roof
When in one row, they are often fused to different degrees.
Symphyotrichum puniceum (Aster puniceus)
(You can click the thumbnails above to get a larger view).
In the tubular (disk flowers) the
nearly always consists of 4 or 5 stamens
that are united by their anthers
and are adnate to
the corolla tube or epigynous zone,
alternate with the lobes.
consists of a single compound
of 2 carpels,
a single 2-cleft style,
and an inferior ovary
with one locule
and one basal ovule.
During maturation of a flower, the style grows through the anther
column, and as it does, hairs on the outer surface of the closed style lobes
brush the pollen
that is released into the anther column to the
where it is available for
in the form of a scale or small cup is commonly found alongside
or around the base of the style.
The fruit is an achene
which may have a persistent pappus
that commonly functions in fruit dispersal.
Subtending and often partly enclosing the florets of the head
is one or more series of usually green, free
connate bracts called
involucral bracts or
Another kind of bract called a
bract or chaff
may be associated with each disk floret throughout the head.
The bracts are in some ways the sepals of the Asteraceae.
One of the best clues for identifying members of the Asteraceae
family is to look for the presence of multiple layers of
bracts beneath the flowers.
In an artichoke, for instance,
those are the scale-like pieces that are pulled off and eaten.
Most members of the Asteraceae family do not have quite that many bracts,
but there are frequently two or more rows.
This is a common pattern of the Aster family.
The genera are sometimes rather ill-defined, which can make the writing of
efficient keys difficult.
Members of the Asteraceae are more commonly in flower
in late Summer and Fall in temperate areas; but in my area,
25 km north of Montréal, one of the first if not the first plant to flower
in the Spring is an Asteraceae, the Tussilago farfara.
Plants belonging to the Asteraceae must then share
all the following characteristics:
None of these traits, taken separately, can be considered
- The inflorescence is a capitulum or flower head.
- The anthers are syngenesious,
i.e. the stamens are fused together
at their edges by the anthers, forming a tube.
- The ovary is with
basal arrangement of the
- There is one ovule per ovary.
- They have a pappus (a tuft of hairs on a fruit).
- Their fruit is an achene.
- They contain sesquiterpenes
in the essential oils,
but do not contain iridoids.
contained in the Asteraceae are thought to function as feeding deterrents.
The sesquiterpene lactones can cause contact
Members of the Asteraceae produce a wide array of toxic compounds,
one of the most famous is Artemesia absinthium (Wormwood),
which produces thujone.
Extracts of Artemesia absinthium
were mixed with alcohol to produce a drink called absinthe.
This drink was popular in Europe for a time but has since been outlawed
in most countries because of the toxicity of thujone.
Vincent Van Gogh supposedly consumed large quantities of absinthe
and his insanity and genius have both been attributed to absinthe.
Commercially important plants in the Asteraceae include
the food crops lettuce, chicory and sunflower.
Other well-known foods are Jerusalem and French
artichokes, or herbal tea like camomile.
The dandelion weed (Taraxacum officinale) is also used as food by many.
Familiar members of the Asteraceae used as cut or garden flowers are
the Asters, Dahlias, Chrysanthemums, Cornflowers and Sunflowers, not to forget
the Edelweiss (Leontopodium alpinum) of alpine gardens.
Members of the Asteraceae
have been used for a wide array of medicinal purposes.
The one that has probably attracted the most interest recently is
Echinacea purpurea (Purple Coneflower),
which produces compounds that stimulate the immune system.
Many members of the Asteraceae family
are copious nectar
producers and are useful for
populations during their bloom.
Helianthus annuus (domestic sunflower),
and some species of Solidago
(Goldenrod) are major honey plants for beekeepers.
Solidago produces relatively high
which helps honeybees overwinter.
The Asteraceae of Québec
The numerous genera are usually divided into 3
and about 18 tribes, as follows:
(In the list below, only the the genera entries with a list of one or more
species entries are found in Québec)
- The subfamily Barnadesioideae, with genera only in South America.
- The subfamily Coliadinae, with the following tribes:
- Tribe Diapensieae with the following genera:
- The subfamily Cichorioideae, with elongated corolla lobes, with
the following tribes:
- Tribe Arctotidae (or Arctoteae), the tribe of the
African Daisies, is a diverse and interesting group with a
primarily southern African distribution (ca. 17 genera,
220 species); e.g. the genus Gazania
(with the species Gazania hybrida being an ornamental plant).
- Tribe Cardueae (or Cynaraeae) with
spinous alternate leaves,
involucral bract spinous or
discoid capitulum (sometimes with larger disk flowers on the
margin), hairy receptacle, bulging style,
e.g. the genera:
with in Québec, the species and
with, in Québec, the species and subspecies:
with, in Québec, the species, subspecies and hybrids:
with, in Québec, the species and variety:
- Echinops, with, in Québec, the species:
- Echinops exaltatus
- Echinops sphaerocephalus
- Silybum, with, in Québec, the species
- (eventually : Tragopogon also this genus
is more often put in the Lactuceae tribe)
- Tribe Eremothamneae, e.g. the genus Eremothamnus.
- Tribe Lactuceae (also called Cichorieae)
with alternate leaves,
e.g. the genera:
- Agoseris. with, in Québec, the species
Cichorium with, in Québec, the single species
- Crepis, with, in Québec, the species:
- Crepis capillaris
- Crepis tectorum
- Glebionis. with, in Québec, the species
Hieraciumwith, in Québec, the species:
- Hieracium albiflorum
- Hieracium caespitosum
- Hieracium flagellare
- Hieracium laevigatum
- Hieracium murorum
- Hieracium paniculatum
- Hieracium pilosella
- Hieracium robinsonii
- Hieracium sabaudum
- Hieracium scabrum
- Hieracium tridentatum
- Hieracium umbellatum
- Hieracium vulgatum
Hypochaeris, with, in Québec, the species
- Lactuca, with, in Québec, the species:
- Lactuca biennis
- Lactuca canadensis
- Lactuca hirsuta
- Lactuca saligna
- Lactuca serriola
- Lapsana, with, in Québec, the species
Leontodon, with, in Québec, the species
- Mulgedium, with, in Québec, the species
- Mycelis, with, in Québec, the species
Prenanthes with 5 species in Québec:
Prenanthes alba that is found
in central and western Québec.
Prenanthes altissima found all over the province.
- Prenanthes boottii
found all over the province.
- Prenanthes racemosa found in eastern Québec.
- Prenanthes trifoliolata
Sonchus, with, in Québec, the species:
Taraxacum, with, in Québec, the species:
- Taraxacum ceratophorum
- Taraxacum erythrospermum
- Taraxacum lapponicum
- Taraxacum latilobum
- Taraxacum laurentianum
- Taraxacum palustre
- Taraxacum phymatocarpum
Tragopogon, with, in Québec, the species:
- Tribe Liabeae with genera only in the Andes.
- Tribe Mutisieae, e.g.
the genera of the lovely ornemental Gerbera.
- Tribe Tarchonantheae.
- Tribe Vernonieae with alternate leaves, discoid capitula,
reddish or bluish flowers, sericeous pappus, e.g. the genus
- The subfamily Asteriodeae with short corolla lobes,
surfaces with 2 marginal
lines, with the following tribes:
- Tribe Anthemideae with alternate leaves,
radiate or discoid capitula,
naked or squarrose receptacle,
pappus a crown of merged scales or without pappus;
e.g. the genera:
Achillea with, in Québec, the species:
- Anthemis with in Québec, the two species:
- Anthemis arvensis
- Anthemis cotula
- Arctanthemum with in Québec, the
Arctanthemum arcticum subsp. polare subspecies
- Artemisia with in Québec, the species:
- Artemisai abrotanum
- Artemisia absinthium
- Artemisia annua
- Artemisia biennis
- Artemisia campestris subsp. caudata
- Artemisia frigida
- Artemisia ludoviciana subsp. ludoviciana
- Artemisia pontica
- Artemisia stelleriana
- Artemisia tilesii
- Artemisia vulgaris
- Cota, with, in Québec, the
Cota tinctoria species
- Cotula, with, in Québec, the
Cotula coronopifolia species
- Leucanthemum, with, in Québec, the species
Matricaria, with, in Québec, the species:
with, in Québec, the species:
- Tripleurospermum, with, in Québec, the species:
- Tripleurospermum inodorum
- Tripleurospermum maritimum
- Tribe Astereae with alternate leaves, radiate or discoid
small capitula, naked receptacle,
and stigma with triangular appendices, sericeous pappus; e.g.
The genus Aster is then now generally restricted to the
Old World species, with Aster amellus being the type
species of the genus (and of the family Asteraceae).
For the time being (and some time to come!),
these pages will keep the old taxonomic classification
in parallel with the new classification; i.e. the genus
Oclemena of the new classification is linked by the
Aster link above, and at the species level,
Oclemena acuminata of the new classification, i.e.
Aster acuminatus of the old one, is linked by an entry
in the Aster link above, and by the species entry
at the genus Oclemena below.
- Bellis with, in Québec, the species:
- Canadanthus with, in Québec, the species:
- Conyza with, in Québec, the species:
- Erigeron, with, in Québec, the species:
- Erigeron acris
- Erigeron annuus
- Erigeron compositus
- Erigeron elatus
- Erigeron humilis
- Erigeron hyssopifolius
- Erigeron lonchophyllus
- Erigeron philadelphicus
- Erigeron pulchellus
- Erigeron strigosus
- Erigeron uniflorus
Eurybia with 3 species in Québec:
- Eurybia divaricata
Eurybia macrophylla (previously usually known as
Aster macrophyllus) that can be found in my area:
- Eurybia radula
Euthamia (that was formerly grouped with the
Solidago genus) with one species in Québec:
- Grindelia, with, in Québec, the species:
- Grindelia hirsutula
- Grindelia squarrosa
- Ionactis, with, in Québec, the species
Oclemena, with, in Québec, the species and
Solidago, with, in Québec, the species:
and the hybrids:
- Solidago altissima
- Solidago bicolor
- Solidago canadensis
- Solidago gigantea
- Solidago hispida
- Solidago juncea
- Solidago leiocarpa
- Solidago lepida
- Solidago macrophylla
- Solidago multiradiata
- Solidago ptarmicoides
- Solidago puberula
- Solidago rugosa
- Solidago sempervirens
- Solidago simplex
- Solidago squarrosa
- Solidago x asperula
- Solidago x beaudryi
- Solidago x calcicola
a variable segregate
genus, with a leaf morphology and general plant habit too diverse to
generalize but for the
(The micromorphological characters, on the other hand,
are relatively consistent). In Québec, one can find the species:
and the hybrids:
- Symphyotrichum x subgeminatum
- Symphyotrichum x tardiflorum
- Tribe Calenduleae, e.g. the genus Calendula
(Marigolds) with, in Québec, the species
- Tribe Coreopsideae with 24 genera and around 50 species that
and often dissected leaves and involucral bracts in two rows, e.g.
the Cosmos genus with, in Québec, a single species :
- Tribe Eupatorieae with
discoid capitula, white or pinkish flowers,
achene with a black layer
in their wall, sericeous pappus;
e.g. the genus:
- Tribe Gnaphalieae. This group is most diverse in South
America, Southern Africa and Australia. It is sometimes commonly
called the pussy's-toes tribe. It has alternate leaves, discoid
capitula, often colored bracts, anthers with a shrunk tip,
a sericeous pappus or no pappus.
- Tribe Helenieae
- Tribe Heliantheae. This is a tribe of closely related genera
of the sunflower family that can be readily recognized due to the
association of a receptacular
bract or chaff scale
with each disk floret in the head.
The heads usually include bisexual,
disk florets with tubular corollas that have 4 or 5
distal lobes and also peripheral
female or sometimes sterile florets
with strap-shaped corollas that have 3 or fewer distal teeth.
However, the ray flowers are sometimes absent
and the heads are then discoid, containing only bisexual florets
with tubular corollas.
The pappus is absent or more commonly ranges from scales
to stiff bristles. The leaves are
opposite or alternate, the capitula are radiate or discoid, at
times nodding, the receptacles are often
scaly or naked, the flowers are
often yellow, the pappus have a black layer in their wall, the
pappus is generally of scales but variable; e.g. the genera:
- Ambrosia, with in Québec, the species:
- Ambrosia artemisiifolia
- Ambrosia psilostachya
- Ambrosia trifida
- Ambrosia x helenae
Bidens, with, in Québec, the species:
- Coreopsis, with in Québec, the species:
- Coreopsis grandiflora
- Coreopsis tinctoria
- Coreopsis tripteris
- Coreopsis verticillata
- Cyclachaena, with in Québec, the species:
- Gaillardia, with, in Québec, the species:
- Gaillardia aristata
- Gaillardia pulchella
Galinsoga, with, in Québec, the species:
- Helenium, with, in Québec, the species:
- Helenium autumnale
- Helenium flexuosum
Helianthus, with, in Québec, the species:
- Helianthus decapetalus
- Helianthus giganteus
- Helianthus grosseserratus
- Helianthus maximilianii
- Helianthus nuttallii
- Helianthus pauciflorus
- Helianthus tuberosus
Heliopsis, with, in Québec, the species
- Madia, with, in Québec, the species:
- Madia glomerata
- Madia sativa
Rudbeckia, with, in Québec, the species:
- Silphium, with, in Québec, the species:
- Tagetes, with, in Québec, the species
Xanthium, with, in Québec, the species:
- Tribe Inuleae, with alternate leaves, radiate capitula,
anthers with a shrunk tip, a sericeous pappus or no pappus;
e.g. the genera :
Anaphalis with only one species in Québec,
Anaphalis margaritacea, but
60 to 100 species in North America and Asia.
Antennaria with the following species and subspecies:
- Antennaria alpina
- Antennaria frieseana subsp. frieseana
- Antennaria howellii subsp. canadensis
- Antennaria howellii subsp. neodioica
- Antennaria howellii subsp. petaloidea
- Antennaria microphylla
- Antennaria monocephala subsp. angustata
- Antennaria neglecta
- Antennaria parlinii subsp. parlinii
- Antennaria parlinii subsp. fallax
- Antennaria pulcherrima subsp. eucosma
- Antennaria pulcherrima subsp. pulcherrima
- Antennaria rosea subsp. confinis
- Antennaria rosea subsp. arida
- Antennaria rosea subsp. pulvinata
- Inula, with, in Québec, the species:
- Inula britannica
- Inula helenium
- Omalotheca, with, in Québec, the species:
- Omalotheca norvegica
- Omalotheca supina
- Omalotheca sylvatica
- Tribe Plucheae.
- Tribe Senecioneae. Its members exhibit probably the widest
possible range of form to be found anywhere in the entire plant
kingdom and include annuals,
minute creeping Alpines,
perennial herbs, shrubs,
climbers, leaf succulents,
stem and root succulents, trees and semi-aquatic plants.
This is a tribe of closely related genera
that can be recognized most readily by the nature of the pappus and
the involucral bracts or
The phyllaries are basically in one well developed,
often partially or wholly connate
series of equal length that closely envelope the head.
Frequently there are a few, very much smaller and mostly randomly
near the base of the main series.
The pappus is of fine, soft, often pure white capillary hairs.
Heads may be either discoid or radiate. The leaves are generally
alternate, the flowers are often yellow, the receptacle is naked,
the pappus is sericeous; e.g. the genera:
- Arnica with in Québec, the species and subspecies
- Arnica angustifolia subsp. angustifolia
- Arnica angustifolia subsp. tomentosa
- Arnica chamissonis
- Arnica griscomii subsp. griscomii
- Arnica lanceolata subsp. lanceolata
- Arnica lonchophylla
- Packera, with, in Québec, the species:
- Packera aurea
- Packera cymbalaria
- Packera indecora
- Packera obovata
- Packera pauciflora
- Packera paupercula
- Packera schweinitziana
- Petasites, with, in Québec, the species
- Senecio, with, in Québec, the species:
- Senecio jacobaea
- Senecio pseudoarnica
- Senecio sylvaticus
- Senecio viscosus
- Senecio vulgaris
- Tephroseris, with, in Québec, the species
Tussilago, with, in Québec, the species: