Family: Poaceae |
J.K Wipff 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. Named for Christen Friis Rottboell (1727-1797), a Danish botanist. SELECTED REFERENCES Hall, D.W. and D.T. Patterson. 1992. Itchgrass-stop the trains? Weed Technol. 6:239-241; Veldkamp, J.F., R. de Koning, and M.S.M. Sosef. 1986. Generic delimitation of Rottboellia and related genera (Gramineae). Blumea 31:281-307; Wipff, J.K. and B.S. Rector. 1993. Rottboellia cochinchinensis (Poaceae: Andropogoneae) new to Texas. Sida 15:419-424. T.A. Cope (1995) Rottboellia. Flora of Somalia 4: 268-269. Plants annual. Ligules membranous, very short. Inflorescences axillary, spikelike rames [spikelike inflorescence branches composed of successive sessile-pedicellate pairs of andropogonoid spikelets, disarticuating below the sessile spikelets]; rames solitary or aggregated into leafy panicles, cylindrical; internodes flattened or smi-cylindrial, partly or woly fusted to the adjacent pedicels. Sessile spikelets sunk into the internodes; calluses truncate, with prominent cenral pegs; lower glumes coriaceous, broadly convex, 2-keeled, smooth, narrowly winged distally; lower florets male, lemmas and paleas hyaline; upper florets bisexual, with entire, unawned lemmas. Pedicellate spikelets herbaceous or scarious, a little smaller than the sessile spikelets; pedicels oblong, flattened, scarcely distinguishable from the internodes. Caryopses ovate in face-view, crescentic in side view. Rottboellia includes about 24 species. They are native to tropical regions through the world but with the majority being native to the New World tropics. One species, Rottboellia cochinchinensis, grows in both Somaliland and Somalia. Global distribution of Rottboellia. Note: GBIF records include introduced and cultivated plants. Consequently, the distribution shown often differs from statements about a taxon's native distribution. |