Panicum altum

HABIT Perennial. Rhizomes elongated. Culms decumbent; reed-like; 200–400 cm long; 3–6 mm diam. Culm-internodes glaucous; smooth. Culm-nodes swollen. Lateral branches lacking, or sparse; extravaginal. Leaf-sheaths smooth. Ligule a ciliate membrane; 2–3 mm long. Leaf-blades 30–45 cm long; 8–15 mm wide. Leaf-blade surface smooth. Leaf-blade margins scabrous.

INFLORESCENCE Inflorescence a panicle.

Panicle open; ovate; 20–30 cm long. Primary panicle branches ascending, or spreading. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; compressed slightly; 3.2–4 mm long; 1.2 mm wide; falling entire.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma; gaping. Lower glume ovate; 0.66 length of spikelet; membranous; without keels. Lower glume lateral veins prominent. Lower glume apex acute. Upper glume ovate; 1 length of spikelet; membranous; 1-keeled; 7 -veined. Upper glume lateral veins prominent. Upper glume apex acute.

FLORETS Basal sterile florets barren; with palea, or without significant palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 length of spikelet; membranous; 1-keeled; 7 -veined; prominently veined; acute. Fertile lemma elliptic; dorsally compressed; 2–2.2 mm long; 1 mm wide; indurate; without keel. Lemma margins involute. Lemma apex acute. Palea involute; indurate.

DISTRIBUTION North America: Mexico. South America: Mesoamericana, Caribbean, northern South America, and Brazil.

NOTES Paniceae. Chase 1994.

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