Panicum arctum

HABIT Annual. Culms decumbent; 5–30 cm long. Culm-internodes 4–6 cm long; distally glabrous. Culm-nodes black; glabrous. Lateral branches ample; arising from lower culm and mid culm. Leaf-sheaths mostly shorter than adjacent culm internode; striately veined; glabrous on surface. Ligule an eciliate membrane; 0.6–1 mm long. Leaf-blades 18–40 cm long; 2–3 mm wide. Leaf-blade surface hispid; densely hairy. Leaf-blade margins tuberculate-ciliate; hairy at base. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle. Peduncle 10 cm long; glabrous.

Panicle open; ovate; effuse; 3–7 cm long; 2–5 cm wide.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate; dorsally compressed; 1–1.2 mm long; 0.5–0.6 mm wide; falling entire. Rhachilla internodes elongated between glumes.

GLUMES Glumes shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 0.5–0.6 mm long; 0.5 length of spikelet; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume apex obtuse, or acute. Upper glume ovate; 0.9 length of spikelet; membranous; without keels; 5 -veined. Upper glume apex obtuse.

FLORETS Basal sterile florets barren; with palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 length of spikelet; membranous; 3–5 -veined; acute. Palea of lower sterile floret 0.6–0.7 mm long. Fertile lemma obovate; dorsally compressed; 1 mm long; indurate; pallid; without keel. Lemma surface smooth. Lemma margins involute. Palea involute; indurate.

DISTRIBUTION South America: northern South America and Brazil.

NOTES Paniceae. Fl Guiana 1995.

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