jaculator n. A hardened and hook-like funicle that is conspicuous in the seeds of many Acanthaceae.

jaculiferous (L. jaculum, jaculi: javelin; ferre: to carry) adj. Having dartlike spines.

joint (L. junctus: tied, bound) n. The section of a stem from which a leaf or branch arises; a node, especially on a grass stem.

jointed (L. junctus: tied, bound) adj. Having nodes or points of articulation, as in the stems of Opuntia.

juga See jugum.

jugate (L. jugum: yoke) adj. With parts in pairs, as the leaflets of a pinnate leaf.

jugum (L. jugum: yoke) n. (pl. juga) A pair of opposite leaflets; a pair of leaves; especially in Fissidens.

julaceous (L. iulis: ament) adj. Smoothly cylindric, like a catkin, referring to stems or branches with strongly imbricate leaves; like an ament, or bearing aments. Syn. amentaceous.

junceous (L. juncus: rush) adj. See junciform.

junciform (L. juncus: rush; forma: shape) adj. Rush-like in form; ressembling Juncus. Syn. junceous.

juvenile (L. juvenilis: young) adj. An early phase of plant growth, usually characterized by non-flowering, vigorous increase in size, and often thorniness; of leaves, formed on a young plant and different in form from the adult leaves.

juvenile water Water contained within magma and which is emitted during volcanic eruptions.

juxtacostal adj. Of the region adjacent to a costa.