Isachne rigens

HABIT Perennial; caespitose. Culms rambling; 100–200 cm long; 0.5–1 mm diam.; wiry. Lateral branches ample. Leaves distichous. Leaf-sheaths longer than adjacent culm internode; glabrous on surface, or pubescent; outer margin hairy. Ligule a fringe of hairs; 0.5 mm long. Leaf-blades lanceolate; 2–5 cm long; 2–5 mm wide; herbaceous; firm. Leaf-blade midrib evident. Leaf-blade surface scabrous; rough on both sides. Leaf-blade margins cartilaginous; scabrous.

INFLORESCENCE Inflorescence a panicle.

Panicle open; oblong, or ovate; 2–5 cm long. Primary panicle branches ascending, or spreading. Panicle branches stiff.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 1–2 mm long.

FERTILE SPIKELETS Spikelets comprising 2 fertile florets; without rhachilla extension. Spikelets ovate, or orbicular; dorsally compressed; 1.8–2 mm long; breaking up at maturity; disarticulating above glumes but not between florets. Rhachilla internodes pubescent.

GLUMES Glumes deciduous; similar; shorter than spikelet; thinner than fertile lemma. Lower glume oblong; 0.66–0.75 length of spikelet; membranous; without keels; 5 -veined. Lower glume surface puberulous. Lower glume apex obtuse. Upper glume orbicular; 0.66–0.75 length of spikelet; membranous; without keels; 5 -veined. Upper glume surface puberulous. Upper glume apex obtuse.

FLORETS Fertile lemma ovate, or orbicular; 1.8–2 mm long; coriaceous; without keel. Lemma margins involute. Lemma apex obtuse. Palea coriaceous; 2 -veined. Palea surface of upper floret puberulous.

FLOWER Anthers 3.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION South America: Mesoamericana, Caribbean, northern South America, and western South America.

NOTES Isachneae. N Amer Fl 1994.

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