Muhlenbergia arizonica

HABIT Perennial; caespitose; clumped loosely. Culms erect, or geniculately ascending; slender; 15–40 cm long. Culm-internodes distally pubescent. Leaf-sheaths keeled; smooth, or scaberulous; glabrous on surface. Ligule an eciliate membrane; 1–2 mm long; entire, or erose; obtuse. Leaf-blades flat, or conduplicate; 2–5 cm long; 1–2 mm wide. Leaf-blade midrib conspicuous. Leaf-blade surface smooth, or scaberulous; rough abaxially; glabrous, or puberulous; hairy adaxially. Leaf-blade margins cartilaginous.

INFLORESCENCE Inflorescence a panicle.

Panicle open; ovate; 5–15 cm long; 4–8 cm wide. Primary panicle branches spreading. Panicle branches capillary.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels filiform.

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 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 oblong; 1 mm long; 0.33–0.4 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; 2.5–3 mm long; membranous; without keel; 3 -veined. Lemma midvein pubescent; hairy below. Lemma lateral veins prominent. Lemma margins pubescent; hairy below. Lemma apex dentate; 2 -fid; acuminate; awned; 1 -awned. Principal lemma awn from a sinus; 0.5–1.5 mm long overall. Palea 1 length of lemma; 2 -veined.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 3; 1.5–1.6 mm long; purple.

FRUIT Caryopsis with adherent pericarp; fusiform.

DISTRIBUTION North America: southwest USA and Mexico.

NOTES Eragrostideae. Gr Baja Cal 1994.

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