Cenchrus spinifex

HABIT Annual. Culms erect, or geniculately ascending; 5–80 cm long. Ligule a fringe of hairs; 0.5–1.5 mm long. Leaf-blades 2–18 cm long; 2–6 mm wide. Leaf-blade margins scaberulous.

INFLORESCENCE Inflorescence a panicle.

Panicle spiciform; linear; 2–8.5 cm long; 0.8–2 cm wide. Primary panicle branches accrescent to a central axis; with sessile scars on axis. Panicle axis angular; bearing deciduous spikelet clusters.

Spikelets subtended by an involucre. Fertile spikelets sessile; 2–4 in the cluster. Involucre composed of bristles; connate into a cup below (cleft on 2 sides); with 2–7 mm connate; ovate, or globose; 5.5–10.2 mm long; base obconical; base glabrous, or pubescent. Involucral bristles deciduous with the fertile spikelets; emerging irregularly from body of a burr; 8–40 in principal whorl; with longest bristle scarcely emergent; 2–5 mm long; flattened; rigid; retrorsely scaberulous; pubescent; spinose.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; acuminate; 3.5–5.8 mm long; falling entire; deciduous with accessory branch structures.

GLUMES Glumes shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 1–1.3 mm long; 0.33–0.5 length of spikelet; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume apex obtuse, or acute. Upper glume ovate; 2.8–5 mm long; 0.75–0.9 length of spikelet; membranous; without keels; 5–7 -veined. Upper glume apex obtuse, or acute.

FLORETS Basal sterile florets barren; with palea. Lemma of lower sterile floret ovate; 1 length of spikelet; membranous; 5–7 -veined; acute. Fertile lemma ovate; 3.4–5.8 mm long; coriaceous; much thinner on margins; without keel; 3 -veined. Lemma margins flat. Lemma apex acute. Palea coriaceous.

FLOWER Anthers 3; 0.5–2 mm long.

FRUIT Caryopsis with adherent pericarp; ovoid; dorsally compressed; 1.3–3 mm long.

DISTRIBUTION Europe: southwestern, southeastern, and eastern. Africa: north, Macaronesia, southern tropical, and south. Asia-temperate: western Asia and China. Asia-tropical: India. Australasia: Australia. North America: northwest USA, north-central USA, northeast USA, southwest USA, south-central USA, southeast USA, and Mexico. South America: Mesoamericana, Caribbean, western South America, Brazil, and southern South America.

NOTES Paniceae. FZ.

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