Acantha

[Gr. thorn, spine.] ( Bot. ) A prickle.(Zool.) A spine or prickly fin. -( Anat. ) The vertebral column; the spinous proce of a vertebra. Acantha'ceæ, n . pl . ( Bot .) An order of plants, alliance Bignonia les , characterized by having axile placente, wingle exalbuminous seeds attached to hard placental proce es, and large fleshy cotyledons. They are nearly related to Scrophulariaceæ , and for the most part tropical. In such regions they are extremely common,constituting a large part of the herbage. For the most part they art mucilaginous and slightly bitter, but generally of little use to man. Many of the species are mere weeds; others bear handsome flowers with gaudy colors, but seldom with any odor; a very small number have been occa sionally employed medicinally as emollients or diuretics. The roots of Acanthacese are either annual or perennial. The stems are usually four-cornered when young, but afterward become nearly round. Their flowers are often enclosed within large, leafy, imbricated bracteæ. The calyx is usually composed of either four or five parts, which overlap each other, and occasionally grow together at the base. The corolla is monopetalous and irregular. The stamens are either two or four, but in the latter case are of unequal lengths. The pistillum is superior and turcilled. The seed-ve el contains two cells, which burst when ripe, often with elasticity, and expose a few roundish seeds hanging to the cells by curiously hooked proce es. The stems of all the species emit roots very readily from their tumid articulations; on which account gardeners universally increase them by cuttings of the full-grown branches. They are always easy to cultivate, provided they are not kept in too cold or too dry a situation. The annual kinds freely produce seeds, by which they are readily multiplied. The most common genera are Justicia, Acanthus, Ruellia, Thun bergia, Barleria, and Eranthemum; q. v. Acan'thice, n. The sweet juice of ivy-buds. Acan'thite, n. ( Min . ) An orthorhombic sulphide mineral of the Galena division. Comp . sulphur 12.9, silver 87-1. Acan'thion, n. ( Pal .) A genus of Rodent i a, known at present only by their osteology. The genus was established by F. Cuvier.