Panicum longum

HABIT Perennial. Culms geniculately ascending; 120–200 cm long. Culm-internodes distally glabrous. Culm-nodes glabrous. Lateral branches lacking, or sparse. Leaf-sheaths subequal to internodes; papillose; glabrous on surface, or hirsute; with tubercle-based hairs. Ligule a ciliolate membrane; 0.5 mm long. Leaf-blade base broadly rounded. Leaf-blades ascending, or spreading; 10–25 cm long; 6–12 mm wide. Leaf-blade surface pilose; sparsely hairy; hairy adaxially; with tubercle-based hairs. Leaf-blade apex attenuate.

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

Panicle open; lanceolate; 20–25 cm long; 2–5 cm wide. Primary panicle branches simple. Panicle axis hispid. Panicle branches secund; hispid.

Spikelets in pairs. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; acute; 2 mm long; 0.9 mm wide; falling entire.

GLUMES Glumes similar; shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 0.5 length of spikelet; membranous; without keels; 3 -veined. Lower glume surface asperulous; rough above and on veins. Lower glume apex acute. Upper glume ovate; 0.9 length of spikelet; membranous; without keels; 3 -veined. Upper glume surface asperulous; rough above and on veins. Upper glume apex acute.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 length of spikelet; membranous; 5 -veined; acute. Fertile lemma elliptic; dorsally compressed; 2.1 mm long; 0.8 mm wide; indurate; without keel. Lemma surface asperulous; rough above. Lemma margins involute. Lemma apex acute. Palea involute; indurate.

DISTRIBUTION North America: Mexico.

NOTES Paniceae. Hitch. & Chase 2000.

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