Bluebunch Wheatgrass

Bluebunch Wheatgrass (Agropyron spicatum)

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

Bluebunch wheatgrass is a native, cool-season, drought-tolerant, perennial bunchgrass. It is abundant throughout the Pacific Northwest, Rocky Mountain states, Great Basin and Northern Great Plains. It is most abundant in parts of Montana, Wyoming, Idaho, eastern Oregon and Washington, often forming stands of up to 60 percent ground cover. It is the state grass of Montana.

Description

Bluebunch wheatgrass grows in large, erect bunches from 2 to 3 feet tall. It has numerous, rather lax, flat (infrequently, lightly-inrolled) leaves situated along the length of the stems. The seed heads are narrow, 3 to 6 inches long. The spikelets are solitary at the points of a zig-zag rachis. Each spikelet is three- to six-flowered, with the seeds tipped by a characteristic, rough, divergent awn. There are four to 12 seed heads per plant. It has an extensive, deep, fibrous root system.

Adaptation

It is a distinctly drought-resistant grass found on shallow, stony, gravelly and sandy soils in grassland areas, and on south-facing slopes and other dry areas in the forested regions. This grass is adapted to areas with average annual precipitation of 8 to 24 inches. It seldom grows on wet soils, and rarely in thick timber. In the plains areas, it is usually found in association with blue grama, western wheatgrass and little bluestem; while in forested regions, it is closely associated with rough and Idaho fescue. It ranges in altitude from 1,400 feet in Nebraska to 9,000 in Wyoming and Colorado.

Limitations

Bluebunch wheatgrass will not tolerate a high water table or poorly- drained sites, and tolerates very little extremes in acidity and alkalinity. If allowed to mature, the stems are quite wiry, discouraging utilization by livestock, particularly sheep. The awns on the seed create some problems in harvesting and handling.

Use for Hay

Native hay of bluebunch wheatgrass is harvested where it is accessible. However, this species is usually found on steep, inaccessible sites. If the plant is mature, the hay will be quite coarse, necessitating harvest at the late boot or early heading stage. The tall, erect stature of the plant makes it easy to mow. Mulching with mature, native hay has been used as a planting technique on critically disturbed areas.

Use for Pasture

The palatability of bluebunch wheatgrass is very good, or even excellent, for cattle, horses and sheep -- except where it is fully cured or has not been grazed for a couple years. Its leafiness enables it to produce a large amount of forage per plant. The leaves remain green throughout the growing season, and the nutritive value remains fairly high in the fall. This grass is favored by elk, and along with rough fescue, makes up a large part of their diet. The growing point for this grass is several inches above the ground, making it very susceptible to continued close grazing. Because this plant reproduces strictly by seed shatter, repeated early grazing will affect bluebunch stands because they are unable to set seed. Periodically deferring grazing until seeds mature enables the plant to reseed itself and utilize cattle trampling to bury the seed.

Seed Production

Bluebunch wheatgrass grown for seed production on medium to coarse, well-drained, irrigated soils will produce 200 to 500 pounds per acre of seed, with isolated production as high as 800 pounds per acre. Seed can be harvested from native stands, yielding 100 to 400 pounds per acre. Although seed heads are formed nearly every year on native sites, the amount of seed fill is determined by the precipitation and climate for that growing season. There are some problems with seed production fields being contaminated with annual bromegrasses. The seeds of these weedy grasses are virtually impossible to totally separate from the bluebunch seed.

* 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.