Muhlenbergia rigida

HABIT Perennial; caespitose; clumped densely. Culms erect; slender; 50–100 cm long. Culm-nodes flush with internodes. Leaf-sheaths without keel. Leaf-sheath auricles erect. Ligule an eciliate membrane; 3–9(–15) mm long; lacerate. Leaf-blades involute; 12–35 cm long; 1–3 mm wide.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; linear, or lanceolate; 10–35 cm long; 2–4(–10) cm wide. Panicle branches capillary.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels filiform; 5–15 mm long.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; laterally compressed; 4–5 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent.

GLUMES Glumes persistent; similar; shorter than spikelet; similar to fertile lemma in texture. Lower glume elliptic, or ovate; 1–1.3(–1.5) mm long; 1 length of upper glume; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume apex obtuse, or acute. Upper glume elliptic, or ovate; 1–1.3(–1.5) mm long; 0.25 length of adjacent fertile lemma; membranous; without keels; 1 -veined. Upper glume lateral veins absent. Upper glume apex obtuse, or acute.

FLORETS Fertile lemma lanceolate; 4–5 mm long; membranous; purple; keeled; 3 -veined. Lemma surface scaberulous; rough above. Lemma apex acute; awned; 1 -awned. Principal lemma awn 10–22 mm long overall. Palea 1 length of lemma; 2 -veined.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 3; 1.8–2.3 mm long; purple.

FRUIT Caryopsis with adherent pericarp; fusiform.

DISTRIBUTION North America: southwest USA, south-central USA, and Mexico. South America: northern South America, western South America, and southern South America.

NOTES Eragrostideae. Gould.

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