GrassBase - The Online World Grass Flora

Descriptions

W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Pennisetum tristachyum

HABIT Perennial; caespitose. Culms erect; robust; 200–250 cm long; 3–6 mm diam. Culm-internodes distally glabrous. Culm-nodes pubescent. Lateral branches ample. Leaf-sheaths glabrous on surface. Ligule a ciliate membrane. Leaf-blades lanceolate; 20–35 cm long; 30 mm wide. Leaf-blade surface glabrous, or pubescent. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle; terminal and axillary.

Panicle spiciform; linear; 5–15 cm long. Primary panicle branches accrescent to a central axis; with lateral stumps on axis. Panicle axis hispid; bearing deciduous spikelet clusters.

Spikelets subtended by an involucre. Fertile spikelets sessile; 1 in the cluster. Involucre composed of bristles; 8–12 mm long; base truncate. Involucral bristles deciduous with the fertile spikelets; numerous; in one whorl; with one conspicuously longer bristle; 20 mm long; terete; flexible; glabrous.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; acute, or acuminate; 5.5–6.3 mm long; falling entire; deciduous with accessory branch structures.

GLUMES Glumes shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 1–1.5 mm long; 0.2–0.25 length of spikelet; membranous; without keels; 0–1 -veined. Lower glume lateral veins absent. Lower glume apex obtuse. Upper glume ovate; 2.5–3 mm long; 0.5 length of spikelet; membranous; without keels; 3 -veined. Upper glume lateral veins obscure. Upper glume apex acute.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret ovate; 5.5–6.3 mm long; 1 length of spikelet; membranous; acute. Fertile lemma ovate; 5–8 mm long; chartaceous; without keel. Lemma surface scaberulous; rough above. Lemma margins flat. Lemma apex acuminate. Palea 1 length of lemma; membranous.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION South America: northern South America, western South America, and southern South America.

NOTES Paniceae. Tovar Gr. Peru 2011.

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