Herbs glabrous, often twining and climbing, with alternate leaves. Flowers perfect, regular, with a double, imbricated calyx often colored. Stamens perigynous. Otherwise as in Chenopodiaceae. Fig. 363.

A small order, containing 6 genera and 21 species, chiefly tropical.

BOUSSINGAUL'TIA, Kunth. Mexican Vine. (Dedicated to the celebrated chemist Boussingault.) Fls. membranous, calyx open, the exterior shorter; tube very short; stigmas 3, subclavate; pericarp membranous; embryo annular with the albumen central. - Vines twining to the right. Lvs. thick, petiolate. Fls. in spicate rac.

B. baselloides Kunth. Lvs. rather fleshy, broadly cordate-ovate, acuminata or the larger ones obtuse, short-petioled; racemes loose, simple or branched; fil. dilated below; stig. sessile. - Cultivated for shades and arbors. A vine of rapid growth, arising many feet. Lvs. 1 - 3' long. Racemes numerous, greenish, † S. Am.