Cenchrus biflorus

HABIT Annual; caespitose. Culms geniculately ascending; 5–90 cm long. Culm-internodes unequal, the upper longer; channelled; hollow; eglandular; smooth; distally glabrous, or pubescent. Culm-nodes constricted; purple; glabrous. Lateral branches ample; extravaginal; arising from lower culm, or mid culm. Branch complement constant; one, or two; with subequal branches; thinner than stem. Leaves basal and cauline. Leaf-sheaths loose; open for most of their length; with flat margins; longer than adjacent culm internode; keeled; scaberulous; glabrous on surface, or pubescent; outer margin glabrous; inner surface glabrous. Leaf-sheath oral hairs ciliate, or bearded. Ligule a fringe of hairs; 2 mm long. Collar dark; pubescent. Leaf-blade base simple, or broadly rounded, or cordate. Leaf-blades linear, or lanceolate; 2–25 cm long; 2–7 mm wide. Leaf-blade surface scaberulous; rough on both sides; puberulous, or pilose (sparsely). Leaf-blade margins scaberulous; glabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle.

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

Spikelets subtended by an involucre. Fertile spikelets sessile; 1–3 in the cluster. Involucre composed of bristles; connate into a disc below (2–4mm diam); with 0.5–1 mm connate; ovate; 4–11 mm long; base obconical; base glabrous. Involucral bristles deciduous with the fertile spikelets; in one whorl, or with an outer whorl of thinner bristles; 7–15 in principal whorl; inner bristles longer than outer; with longest bristle scarcely emergent; 2.9–7 mm long; flattened; grooved on the face; rigid; retrorsely scaberulous; ciliate; obtuse, or spinose.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; acuminate; 3.5–6 mm long; 1–1.5 mm wide; falling entire; deciduous with accessory branch structures.

GLUMES Glumes shorter than spikelet; thinner than fertile lemma. Lower glume lanceolate; 0.4–0.5 length of spikelet; membranous; without keels; 0–1 -veined. Lower glume lateral veins absent. Lower glume apex obtuse, or acute. Upper glume ovate; 2.5–3.5 mm long; 0.6–0.7 length of spikelet; membranous; without keels; 1–5 -veined. Upper glume apex obtuse, or acute.

FLORETS Basal sterile florets barren; with palea, or without significant palea. Lemma of lower sterile floret similar to upper glume; ovate; 0.7–0.8 length of spikelet; membranous; 3–5 -veined; acute; muticous, or mucronate. Fertile lemma ovate; 3.5–6 mm long; coriaceous; much thinner on margins; without keel; 5 -veined. Lemma margins flat. Lemma apex acute. Palea coriaceous.

FLOWER Anthers 3; 0.4 mm long; brown; anther tip smooth. Filaments 2 mm long. Stigmas yellow. Styles 2.2 mm long. Ovary glabrous.

FRUIT Caryopsis oblong, or orbicular; 1.1–1.3 mm long.

DISTRIBUTION Africa: north, west tropical, west-central tropical, northeast tropical, east tropical, southern tropical, south, and western Indian ocean. Asia-temperate: western Asia and Arabia. Asia-tropical: India. Australasia: Australia.

NOTES Paniceae. VJN 1993.

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