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Blue Grama (Bouteloua gracilis)

Plant Species
From Montana Interagency Plant Materials Handbook *
 By
S. Smoliak, R.L. Ditterline, J.D. Scheetz, L.K. Holzworth, J.R. Sims, L.E. Wiesner, D.E. Baldridge, and G.L. Tibke

Blue grama is a native, warm-season, low-growing, perennial bunchgrass. It dominates more than one-third of the total usable range in Arizona and New Mexico, and is prominent throughout the Great Plains' states on into Canada. The stature and productivity decreases as you move to the northern latitudes.

Description

Blue grama grass is a low, sod-forming bunchgrass with fine, curling, basal leaves of a greyish-green color. The leaves are commonly 2 to 5 inches long and less than 1/8 inch wide. They have distinctive hairs at the junction of the leaf blade and stem. The flowering stems are 6 to 12 inches in height, slender and distinctively jointed. Each flowering stem usually has two (varying from one to four), one-sided, purplish spikes extending at a sharp angle from the main stem. The spikes vary from 1 to 2 inches long. At maturity, the spikes become golden brown and tend to curve backwards. The root system is made up of dense masses of fine roots concentrated in the surface 2 1/2 feet of soil. Blue grama is sometimes confused with buffalo grass; however, buffalo grass has above-ground runners (stolons), while blue grama does not.

Adaptation

Blue grama is found from the southern plains of Canada to Mexico. In the southwest, it occurs on dry plains, foothills and plateaus. Its greatest abundance is in the short-grass region of west Texas and eastern New Mexico, and in the pinyon-juniper woodlands of Arizona and New Mexico. It is found at elevations of 3,500 feet on the southwest plains, at 8,500 feet in the San Francisco Mountains of Arizona, and even at 10,000 feet in New Mexico. It will endure temperature ranges from -40F to 110F. In the northern latitudes, it becomes prominent on heavily-grazed and trampled rangelands and arid, low-productive ranges. In Montana, it will grow on grasslands varying from 2,000 to 5,000 feet. Blue grama is slightly alkaline-tolerant. It is found on a wide range of soils, but favors the more coarse, well-drained soils.

Limitations

Blue grama is a relatively low forage producer, particularly in the northern latitudes. When it increases on overgrazed land, it tends to form a matted sod, restricting the re-establishment of more favorable grasses. The released cultivars are of southern origin, and do not do well in Montana and Wyoming. Only in the wettest years do native stands produce enough seed to be harvested commercially.

Use for Hay

The low growth form and relatively poor forage production of blue grama make it a poor hay crop. Only under the best moisture conditions will this species produce enough forage to harvest. Although forage production is low, the quality of the forage is high, with the crude protein being around 13 percent for early growth and 6.5 percent for mature cured forage. The harvest of native hay and its use as mulch is a good method of reseeding blue grama.

Use for Pasture

Blue grama is rated as a choice forage species for all classes of livestock. Growth does not occur until the onset of summer warmth and moisture. Blue grama is a quick-growing species, maturing in about 60 to 70 days. Under severe drought conditions, it will go dormant and resume growth when moisture conditions are again favorable. This grass is very well suited for fall and winter grazing, as it cures well and maintains a high nutritive value. It produces very little forage in the spring and early summer. On some of the southwestern grasslands, blue grama is classified as climax vegetation. However, on most ranges, it increases as the bunchgrasses and tall grasses are eliminated by grazing pressure. Blue grama is susceptible to heavy use by rodents.

Seed Production

Native stands produce seed of varying quality and viability. Only in years of above-average precipitation will adequate seeds be produced. Native stands are most often harvested with bluegrass strippers, but they can be direct combined. Under irrigated conditions, blue grama will produce up to 200 pounds per acre of seed. Native harvest usually yields less than 100 pounds per acre. The blue grama spikelet consists of an awned, fertile floret and an awned, densely-bearded, rudimentary floret. These appendages make the seed light and fluffy, requiring some kind of debearding treatment. The primary market for blue grama seed in the Northern Great Plains states is for inclusion in mixtures for land reclamation related to strip mining and mineral development.
 

* The Montana Interagency Plant Materials Handbook (EB69) is no longer in print, but is available for viewing in
Montana County Extension Service and National Resource Conservation Service Offices.