Panicum mertensii

HABIT Perennial. Rootstock evident. Culms erect; robust; 200–300 cm long; 4–8 mm diam.; without nodal roots, or with prop roots. Culm-internodes distally glabrous. Lateral branches lacking. Leaf-sheaths glabrous on surface. Leaf-sheath auricles erect. Ligule a ciliolate membrane; 2–3 mm long. Leaf-blades tapering towards tip and sheath; 30–60 cm long; 14–25 mm wide; dark green. Leaf-blade midrib conspicuous. Leaf-blade surface glabrous.

INFLORESCENCE Inflorescence a panicle. Peduncle 2–5 cm long.

Panicle open; ovate; 40–50 cm long; 17–30 cm wide. Primary panicle branches whorled at most nodes; simple; 8–16 cm long. Panicle branches stiff; straight.

Spikelets solitary, or in pairs. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate; dorsally compressed; subacute; 3.5–4 mm long; falling entire.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume oblate; 1.4–1.7 mm long; 0.25–0.33 length of spikelet; membranous; without keels; 3–4 -veined. Lower glume apex acute. Upper glume ovate; 3.2–3.8 mm long; 1 length of spikelet; membranous; without keels; 9 -veined. Upper glume apex acute.

FLORETS Basal sterile florets barren; with palea. Lemma of lower sterile floret similar to upper glume; ovate; 3.2–3.7 mm long; 1 length of spikelet; membranous; 9 -veined; acute. Fertile lemma ovate; dorsally compressed; 2.7–3 mm long; indurate; shiny; without keel. Lemma margins involute. Lemma apex acute. Palea involute; indurate.

FLOWER Anthers 3; 1.4 mm long; purple.

FRUIT Caryopsis ellipsoid; 1.6 mm long.

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

NOTES Paniceae. Fl Costa Rica 1994.

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