Muhlenbergia laxa

HABIT Perennial. Culms decumbent; 40–70 cm long. Culm-internodes distally glabrous. Lateral branches ample. Leaf-sheaths mostly shorter than adjacent culm internode; without keel; glabrous on surface. Ligule an eciliate membrane; 1 mm long. Leaf-blades 2–5 cm long; 1–2 mm wide. Leaf-blade surface scaberulous.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; linear, or lanceolate; interrupted; 4–6 cm long. Primary panicle branches appressed. Panicle axis scaberulous. Panicle branches pubescent.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels pubescent.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; laterally compressed; 2.5–3 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume oblong; 1.5 mm long; 1 length of upper glume; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume surface scabrous. Lower glume apex dentate; 2 -fid; acute; awned; 1 -awned. Lower glume awn 1.5 mm long. Upper glume oblong; 1.5 mm long; 0.5–0.6 length of adjacent fertile lemma; membranous; without keels. Upper glume surface scabrous. Upper glume apex dentate; 2 -fid; acute; awned; 1 -awned. Upper glume awn 1.5 mm long.

FLORETS Fertile lemma lanceolate; 2.5–3 mm long; membranous; without keel; 3 -veined. Lemma lateral veins excurrent. Lemma surface scaberulous; rough above. Lemma apex awned; 1 -awned. Principal lemma awn 4–8 mm long overall. Palea 1 length of lemma; 2 -veined. Palea apex with excurrent keel veins.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 3.

FRUIT Caryopsis with adherent pericarp; fusiform.

DISTRIBUTION North America: Mexico.

NOTES Eragrostideae. Hitchcock 2002.

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