| | + | Flowers small, white or purplish, 2-lipped, borne in corymbed cymes or clusters. The genus contains not more than 16 species, 2 N. American, 2 Mexican, and the others S. American. They are somewhat woody, and usually have small Lvs.: the whorls of fls. are sometimes loosely corymbose, sometimes axillary, few-fld., much shorter than the Lvs., sometimes many-fld., in dense spikes or terminal heads; calyx 10-13-nerved, 5-toothed; perfect stamens 2. |