by Emily Nelson, Native Plants Class 2002
Common names: Side-oats Grama, Tall Grama
Family: Poaceae - Gramineae
Synonymy:
Etymology:

Identification
Growth form: Side-oats grama is a tufted bunch grass.
Roots: The roots are typically course and fibrous and may grow 2-4 ft in length. They can also grow laterally 1-1.5 ft in the top few inches of soil. Side-oats grama also has short, scaly rhizomes (3, 2, 6, 7).
Stem: Side-oat grama culms are erect and slender, usually about 35 to 100 cm tall (2).
Leaves: Leaf blades are flat or partially involute near the tips, and 2 – 5 mm wide (3, 2). The sheaths are rounded, and like the blades, both are often covered with long, stiff, pustulate hairs, particularly on the leaf margins (2).
Inflorescence/flowers: Side-oats gramas have about 20 to 50 purplish spicate branches (1 cm long), which hang pendulant and mostly twisted to one side of the upper 8 to 25 cm of the culms. Each spike usually contains 2 to 6 ascending, perfect spikelets (6 -10 mm long) (3, 2).
Fruit:
Similar species: The Bouteloua genus contains about 40 species, all Native to the Americas, with high concentration in the southwest United States (2). All species have one or two inflorescences to multiple unilateral, spicate branches with a secund arrangement of spikelets (all face to one side). Bouteloua curtipendula is unique with respect to the 20 to 50 spicate branches per culm as well as being a perennial (2, 4).

Ecology
Life history: Perennial (3)
Native/introduced: U.S. Native (2)
Photosynthetic pathway: C4 (5)
Phenology: Flower stalks usually appear about late June or early July and continue on through September (7). Seedlings are hardy and grow quickly, usually occurring simultaneously with late summer rains (2, 1).
Distribution: In Arizona, Side-oats grama occurs mostly from 2,500 to 7,000 feet in elevation, in openings of the Ponderosa pine, Chaparral, Pinyon-Juniper Woodland, and Desert grassland ecosystems (2).

Uses
Forage: Side-oats grama grass is considered one of the most valuable forage species at mid to high elevations in Arizona (2). It is particularly important for livestock and wildlife because it provides green forage early in the spring and remains green late into the fall (6, 7).

References
1. Frasier, G. W.; Cox, J. R.; Woolhiser, D. A. 1987. Wet-dry cycle effects on
warm-season grass seedling establishment. Journal of Range Management.
40(1): 2-6.

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

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

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

5. Qi, M.Q. and R.E. Redmann. 1993. Seed germination and seedling survival
of C3 and C4 grasses under water stress. 24(3): 277-285.

6. U.S. Department of Agriculture, Forest Service. 1937. Range plant handbook.
Washington, DC. 532 p.

7. Weaver, J. E. and F.W. Albertson. 1956. Grasslands of the Great Plains.
Lincoln, NE: Johnsen Publishing Company. 395 p.