Plants perennial; cespitose, not rhizomatous. Culms 60-130 cm, stout, erect; internodes mostly smooth, sometimes scabridulous below the nodes. Sheaths shorter or longer than the internodes, smooth or scabridulous, not becoming spirally coiled, basal sheaths rounded; ligules 10-30 mm, firm and brown basally, membranous distally, acuminate to obtuse; blades (10)20-65 cm long, 3-6 mm wide, flat or inrolled at the margins, scabrous abaxially, scabridulous or smooth adaxially. Panicles 15-55 cm long, 1-15 cm wide, contracted to open, greenish-tan to purplish; primary branches 3-13 cm, narrowly ascending or diverging up to 60° from the rachises, stiff, spikelet-bearing to the base, lower branches with 30-60 spikelets; pedicels 0.1-2.5 mm, usually shorter than the spikelets, scabridulous or smooth, strongly divergent. Spikelets 2-3.5 mm. Glumes subequal, 2-3.5 mm, usually longer than the florets, scabridulous or smooth, 1(2)-veined, acute to acuminate, usually unawned, rarely awned, awns to 0.2 mm; lemmas 2-2.9 mm, oblong-elliptic, tan to purplish, smooth or scabridulous, apices acute, often bifid, teeth to 0.2 mm, unawned or awned, awns to 2 mm; paleas 2-3 mm, oblong-elliptic, scabridulous or smooth, acute; anthers 1-2.1 mm, yellowish to purplish. Caryopses 1.1-1.5 mm, fusiform, reddish-brown. 2n = 22, 24, 29, 30.

Muhlenbergia longiligula grows on rocky slopes, canyons, and rock outcrops derived from volcanic or calcareous parent materials, at elevations of 1220-2500 m. It is a common species in Arizona and southwestern New Mexico, and extends into northwestern Mexico. It may be confused with M. emersleyi, but differs from that species in its rounded basal leaf sheaths, glabrous lemmas, and panicle branches that are spikelet-bearing to the base. It is also similar to M. lindheimeri, but differs in its rounded basal sheaths.

Common Name: longtongue muhly

Duration: Perennial

Nativity: Native

Lifeform: Graminoid

General: Tufted perennial with stout erect stems 60-130 cm, internodes mostly smooth, sometimes minutely roughened below the nodes, sheaths rounded at the base.

Vegetative: Blades flat to involute 20-65 cm long, 3-6 mm wide, scabrous below, minutely roughened or smooth above, ligules 10-30 mm long, firm and brown basally, membranous.

Inflorescence: Contracted to open panicles 15-55 cm long, 1-15 cm wide, greenish tan to purplish, dense with primary branches 3-13 cm, narrowly ascending or diverging up to 60 degrees from rachises, stiff, spikelet bearing to the base, lower branches with 30-60 spikelets; spikelets 2-3.5 mm, subequal glumes, 2-3.5 mm, longer than florets, minutely roughened or smooth, 1-veined, acute to acuminate, unawned to rarely awned with awns 0.2 mm; lemmas 2-3 mm, oblong-elliptic, glabrous or scabrous, with acute apices, often bifid with teeth to 0.2 mm, unawned or awned with awns to 2 mm.

Ecology: Found on rocky slopes and along ledges, often in canyons and on rock outcrops of volcanic or calcareous parent materials from 5,000-9,000 ft (1524-2743 m); flowers July-October.

Notes: Can be easily confused with M. emersleyi but is distinguished by the base of the sheath being rounded rather than compressed keeled, the glabrous lemmas, and having panicle branches that are spikelet-bearing to the base.

Ethnobotany: Unknown

Etymology: Muhlenbergia is named for Gotthilf Heinrich Ernst Muhlenberg (1753-1815) a clergyman and botanist from Pennsylvania; longiligula means having a long ligule.

Synonyms: None

Editor: SBuckley, 2010