Pennisetum riparium

HABIT Perennial; mat forming. Rhizomes elongated. Stolons present. Culms decumbent; 10–150 cm long. Ligule a fringe of hairs. Leaf-blades flat, or conduplicate; 4–30 cm long; 2–10 mm wide.

INFLORESCENCE Inflorescence a panicle; embraced at base by subtending leaf.

Panicle spiciform; linear; 2–15 cm long. Primary panicle branches accrescent to a central axis; with sessile scars on axis. Panicle axis angular; scaberulous; glabrous; bearing deciduous spikelet clusters.

Spikelets subtended by an involucre. Fertile spikelets sessile; 1–2 in the cluster. Involucre composed of bristles; oblong; 3–6 mm long; base obtuse. Involucral bristles deciduous with the fertile spikelets; numerous; with one conspicuously longer bristle; 7–15 mm long; terete; flexible; glabrous.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; acute, or acuminate; 6–10 mm long; falling entire; deciduous with accessory branch structures.

GLUMES Glumes dissimilar; shorter than spikelet; thinner than fertile lemma. Lower glume oblate; 0.05 length of spikelet; hyaline; without keels; 0 -veined. Lower glume lateral veins absent. Lower glume apex truncate. Upper glume ovate; 0.25–0.33 length of spikelet; hyaline; without keels; 1 -veined. Upper glume lateral veins absent. Upper glume apex obtuse, or acute.

FLORETS Basal sterile florets male, or barren; with palea. Lemma of lower sterile floret ovate; 0.8–1 length of spikelet; membranous; 5–7 -veined; acute. Fertile lemma ovate; 6–10 mm long; membranous; without keel; 5–7 -veined. Lemma margins flat. Lemma apex acute. Palea membranous.

FLOWER Lodicules absent. Anthers 3; 3 mm long; anther tip smooth. Styles connate below.

DISTRIBUTION Africa: northeast tropical and east tropical.

NOTES Paniceae. FTEA.

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