Muhlenbergia minutissima (Steud.) Swallen.

by Emily Nelson, Native Plants Class 2002
Common names: Annual Muhly
Family: Poaceae - Gramineae
Synonymy: Muhlenbergia texana Buckl., Sporobolus microspermus (Lag.) Hitcho., Sporobolus confuses Auct. non (Fourn.) Vasey.
Etymology: “minutissima” means small.

Identification
Growth form: Annual Muhly is a small open panicle grass ground cover that is soft and delicate in appearance.
Roots: The root system consists of short fibrous roots.
Stem: Annual Muhly has delicate culms that are erect to spreading and branching from the base (10 to 35 cm tall) (2). Open panicles occur at about half to three-fourths of the entire plant height, and are 10 to 18 cm long (2, 1).
Leaves: The blades are flat or partially involute when drying and less than 10 cm long and about 1 mm wide (2, 1).
Inflorescence/flowers: Spikelets are usually 1 to 1.7 cm long and green in color on spreading pedicels (2 to 5 mm long), and awnless or with a short (0.1 to 0.8 mm) awn (1). Monecious flowers are one per spikelet (1).
Fruit:
Similar species: The Muhlenbergia genus holds about 120 species with very few that are annuals (1). M. minutissima is similar to M. eludens except for the spreading pedicels that are 2 to 5 mm long, lemma 1 to 1.7 mm long, and absence or extremely short awn (1). M. eludens has appressed pedicels, usually less than 2 mm long, lemma 2 to 2.5 mm long and awn 1.5 to 3.5 mm long (1)

Ecology
Life history: Annual (2).
Native/introduced: U.S. Native (1).
Photosynthetic pathway: C4 (4).
Phenology: In Arizona, Annual Muhly flowers from August to October (1).
Distribution: Normally found on moist, sandy or rocky slopes from Montana to Washington, south to northern Mexico (A). In Arizona, Annual Muhly typically occurs between 4,000 to 9,000 feet in elevation in Apache, Coconino, Yavapai, Greenlee, Gila, Cochise, Pima, and Santa Cruz counties (1).

Uses
Ethnobotanical: Used as a Navajo cooking utensil, ceremonial paintbrush, and in long bundles as ceremonial hairbrushes by Navajo women (3). Also Annual Muhly is considered an indicator species of good soil (3).

References
1. Gould, F.W. 1951. Grasses of the southwestern United States. The University of Arizona Press, Tucson. 143 p.

2. Hitchcock, A.S. 1950. Manual of the grasses of the United States. USDA. 200: 534-435.

3. Hogan, P. and K. Huisinga. 1999. Bouteloua curtipendula. An annotated catalog of the native and naturalized flora of Arizona. 54 p.

4. Watson, L. and M.J. Dallwitz. 1992. The grass genera of the world. University Press, Cambridge. 602 p.