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ROTTBOELLIA L.f.
Plants hermaphroditic, caespitose, annual. Culms erect or ascending; internodes solid, glabrous or scabrous,
terete; nodes glabrous. Leaves mostly cauline, not distinctly distichous; sheaths terete (lower
sharply hispid), margins open; auricles absent; ligules a ciliate membrane; blades flat or involute, linear,
lax, apex acuminate. Spicate racemes terminal and axillary (several inflorescences per culm), sheaths
subtending inflorescences not inflated or spathe-like; rachis glabrous; pedicels not longitudinally grooved,
glabrous, cross-section thin and concave. Spikelets paired (except at the inflorescence apex),
sessile (or short pediceled) spikelets fertile; pedicellate (or long pediceled) spikelets reduced,
staminate or sterile. Pedicellate spikelets reduced, awnless. Sessile spikelets perfect; first glumes
2-keeled, without gland-like depressions or pits, coriaceous; abaxial surface flat or convex,
glabrous, awnless; second glumes length equal to first glumes; lower floret staminate; lemmas
hyaline, entire, awnless; paleas present (well developed) hyaline; upper florets perfect; lemmas
hyaline, entire, awnless; paleas present, hyaline. Stamens 3; anthers yellow. Caryopses small,
obovate, dorsiventrally compressed, yellow. The base chromosome number x=9 or 10.
A small genus of about four species from tropical and subtropical Africa. Our species is an important
noxious weed. The species can become weeds in cultivated crops.
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