Plants perennial; rhizomatous, loosely cespitose. Culms 100-300 cm tall, 3-6 mm thick, erect or ascending, woody below, branching at the middle and upper nodes, branches numerous, fascicled, and spreading; internodes glabrous for most of their length, puberulent or glaucous below the nodes. Sheaths glabrous, enlarged and flattened basally, somewhat chartaceous; ligules 0.2-0.6 mm, membranous, truncate; blades of the branch leaves 1.2-8(12) cm long, 0.7-2.2 mm wide, flat or involute, glabrous abaxially, hirtellous adaxially; blades of the cauline leaves, particularly the lower cauline leaves, absent or greatly reduced. Panicles numerous, terminal on the main culms and the branches, 1-4 cm long, 0.3-1.4 cm wide, lax, inconspicuous; primary panicle branches appressed or loosely spreading up to 40° from the rachises; pedicels 0.1-1.5 mm. Spikelets 2.2-3.1 mm, green or purplish. Glumes subequal, 1-1.7 mm, glabrous, 1-veined, acute to acuminate, occasionally mucronate, mucros to 0.5 mm; lemmas 2.3-3.1 mm, lanceolate, appressed-pubescent on the calluses and lower portion of the margins, apices acuminate, awned, awns 1-5 mm, flexuous; paleas 2.3-3.1 mm, narrowly lanceolate, appressed-pubescent basally, acuminate; anthers 1.5-2 mm, purplish. Caryopses 1.2-1.6 mm, fusiform, reddish-brown. 2n = 40.
Muhlenbergia dumosa grows on rocky slopes, canyon ledges, and cliffs, in areas protected from grazing animals in oak-pine and thorn-scrub forests and oak-grama savannahs, at elevations of 600-1800 m, from Arizona to southern Mexico.
The bladeless cauline leaves and abundant branching from the middle and upper nodes make 'Bamboo Muhly' a very apt English name. North American Indians used it, after boiling, for chest and bowel ailments. It is native from southern Arizona to southern Mexico, but is also grown as an ornamental in the southwestern United States.
FNA 2003, Gould 1980
Common Name: bamboo muhly Duration: Perennial Nativity: Native Lifeform: Graminoid General: Loosely cespitose, rhizomatous perennial grass with stems 1-3 m tall, 3-6 mm thick, erect or ascending, woody below, branching at middle and upper nodes, with many fascicled and spreading branches. Vegetative: Sheaths glabrous, enlarged and flattened basally, with a somewhat papery texture; ligules less than 1 mm, membranous, truncate; blades of branch leaves 1-8 cm long, 0.5-2 mm wide, flat or involute, glabrous below hirtellous above; blades of cauline leaves Inflorescence: Panicles numerous, terminal on main stems and the many branches 1-4 cm long, 0.5-1.5 cm wide, lax, inconspicuous; primary branches appressed or loosely spreading to 40 degrees from the rachises; pedicels 0.1-1.5 mm; spikelets 2-3 mm, green or purplish; glumes subequal, 1-2 mm, glabrous, occasionally mucronate, the mucros to 0.5 mm long; lemmas 2-3 mm, lanceolate, appressed-pubescent on the calluses and lower portion of the margins, apices acuminate, awned, awns 1-5 mm, flexuous. Ecology: Found on dry rocky slopes, canyon ledges, along cliffs below 6,000 ft (1829 m); flowers January-May. Distribution: s AZ, south to s MEX Notes: Muhlenbergia is a large and diverse genus primarily distinguished by having single-flowered spikelets with unequal glumes. To identify M. dumosa, look for the leafless main stem with covered with bladeless sheaths (source of its common name bamboo muhly), abundant branching from the middle and upper nodes, and dense, narrow, almost filiform leaves on the upper branches. Look also for the short, few-flowered panicles on the branch tips with short <5 mm awns on the spikelets. Ethnobotany: Used, after boiling, for chest and bowel ailments. Also grown as an ornamental in the southwestern United States. Etymology: Muhlenbergia is named for Gotthilf Heinrich Ernst Muhlenberg (1753-1815) a clergyman and botanist from Pennsylvania; dumosa means bushy, shrubby. Synonyms: None Editor: SBuckley 2010, AHazelton 2015