ABSTRACT
It comprises herbaceous or semi-frutescent plants that have basal rosettes of leaves, rarely with alternate arrangement. The flowering stem has a terminal spiciform inflorescence, lacks stem leaves, rarely can be branched, and has leaves arranged in a decussate-opposite manner. The leaves are petiolate, without stipules, entire (occasionally divided), with arcuate venation. The flowers are hermaphroditic, actinomorphic, of type 4, grouped in spiciform inflorescences or, occasionally, capituliform, and very rarely solitary. The floral envelope consists of a gamosepalous, persistent calyx and a gamopetalous, tubular corolla with 4 membranous laciniae. The androecium consists of 4 stamens that protrude from the corolla tube to which they are attached. The ovary is superior, with central placentation and apotropous ovules. The fruit can be a polispermous capsule that dehisces through a superior cap (pyxidium) or an achene. 1 - 4
