FTA: 621 (1920); Gen. Gram.:279 (1986).
- Type-species: Acroceras oryzoides (Sw.) Stapf = A. zizanoides (Kunth) Dandy.
Commelinidium Stapf, FTA 9: 627 (1920).
Description:
* Rhizomatous or stoloniferous annuals or perennials. Culms trailing or erect, often spreading and much-branched and rooting from the lower nodes. Leaves linear to ovate, cordate and somewhat aplexicaul, sometimes with cross veins; ligule a narrow hairy membrane or a fringe of hairs.
* Inflorescence composed of loose racemes along a central axis, sometimes subpaniculate due to secondary branching; spikelets in pairs, sometimes solitary, pedicellate, unilaterally on the triquetrous rhachis; pedicels of each pair connate at the base.
* Spikelets lanceolate to oblong, plump with lemmas laterally compressed and thickened at their tip into a small thickened crest. Lower glume short, 3-nerved; upper glume and lower lemma as long as spikelet, lower palea present; upper lemma indurate, smooth or finely striate, margins enrolled, glabrous or puberulous at the green keeled tip; tip of upper palea briefly reflexed and protruding from the lemma. Stamens 3, stigmas 2. Caryopsis ellipsoid, flattened on one side.
African and Indomalayan genus with a twenty species; 12 endemic species in Madagascar, in the WNSA region 3 species.
From the Greek akros (at the top) and keras (a horn), alluding to crested lemmas.