Plants annual; cespitose. Culms 30-300+ cm, glabrous or sparsely pubescent below the nodes, branching above the bases. Leaves mostly cauline, not aromatic; sheaths sometimes with papillose-based hairs; auricles absent; ligules membranous, ciliate; blades flat. Inflorescences terminal and axillary, solitary rames with more than 1 spikelet unit, spikelets partially embedded in the rame axes; disarticulation in the rame axes. Spikelets heterogamous, in sessile-pedicellate pairs, dorsally compressed, unawned. Sessile spikelets with 2 florets; lower glumes coriaceous, smooth or scabridulous, not pitted, 2-keeled, narrowly winged above; upper glumes coriaceous, 1-keeled, winged; lower florets staminate or sterile; upper florets bisexual; lemmas and paleas hyaline; anthers 3; ovaries glabrous. Pedicels thick, fused to the rame axes. Pedicellate spikelets sterile or staminate; glumes herbaceous. Caryopses with a hard endosperm, x = 9,10.
Distribution
Puerto Rico, Ga., Tex., La., N.C., Ark., Miss., Ind., Fla.
Discussion
Rottboellia is a genus of five species, all native to tropical Africa and Asia, represented in all tropical regions of the world by R. cochinchinensis, the species that has been introduced into the Flora region.