Hyparrhenia umbrosa

HABIT Perennial; caespitose. Rhizomes short. Butt sheaths glabrous. Culms decumbent; robust; 130–200 cm long; 3–6 mm diam.; with prop roots. Leaves cauline. Ligule an eciliate membrane; 2 mm long. Leaf-blades 30–60 cm long; 6–12 mm wide. Leaf-blade surface glabrous.

INFLORESCENCE Synflorescence compound; paniculate; 20–30 cm long; dense. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; embraced at base by subtending leaf, or enclosed. Spatheole ovate; 1.2–2.3 cm long; membranous; brown; glabrous, or pilose. Peduncle 0.3–1.3 cm long; pilose above.

Racemes 2; paired; deflexed; 1 cm long; bearing few fertile spikelets; bearing 2–3 fertile spikelets on each. Rhachis fragile at the nodes; ciliate on margins. Rhachis hairs white. Rhachis internodes linear. Rhachis internode tip oblique; flat. Raceme-bases flattened; subequal; 0.5 mm long; stiffly setose.

Spikelets appressed; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; flattened; ciliate; tip oblique.

STERILE SPIKELETS Basal sterile spikelets well-developed; on lower raceme 2 in number; 0 in upper raceme; lanceolate; 5–6 mm long; larger than fertile. Basal sterile spikelet glumes villous; smooth on margins; lower glume muticous.

Companion sterile spikelets well-developed; containing empty lemmas, or male; lanceolate; dorsally compressed; 5–6 mm long; longer than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; villous; acute; muticous, or mucronate. Companion sterile spikelet lemmas 2; enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 4 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; 0.4 mm long; pubescent; base obtuse (broadly); attached obliquely.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of spikelet; coriaceous; without keels; keel-less except near apex. Lower glume surface villous. Lower glume apex dentate; 2 -fid. Upper glume linear; coriaceous; without keels.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 1 length of fertile lemma; hyaline; 2 -veined. Fertile lemma linear; membranous; without keel; 1 -veined. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 7–13 mm long overall; with twisted column. Column of lemma awn puberulous, or pubescent; with 0.2–0.4 mm long hairs. Palea absent or minute.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 3. Stigmas 2.

DISTRIBUTION Africa: west tropical, west-central tropical, northeast tropical, east tropical, and south.

NOTES Andropogoneae. WDC.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.