Thickspike Wheatgrass

Thickspike Wheatgrass (Agropyron dasystachyum)

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

Thickspike wheatgrass is a native, cool-season, drought-tolerant, sod-forming, perennial grass. It generally grows in mixed and sparse stands with western wheatgrass and needlegrasses. It is the most widely distributed of native grasses in the prairie region of the United States and southern Canada.

Description

It is a long-lived, perennial grass with good drought tolerance. The root system of thickspike wheatgrass is made up of a combination of creeping, underground rootstocks, a dense, shallow, fibrous root system (4 to 12 inches) and a few deep roots that penetrate below 2 feet. This combination of roots make this plant quite drought-tolerant. Although this species is rhizomatous, it does develop small tufts of plants that are 18 to 30 inches tall. The leaves of thickspike wheatgrass are similar to western wheatgrass, except the leaves are finer and slightly greener. The glumes, lemma and palea are mostly pubescent. This plant is very similar to streambank wheatgrass, which has little or no pubescence.

Adaptation

Thickspike wheatgrass is adapted to a wide range of soils, but prefers medium- to coarse-textured and granular clay soils, slightly acid to moderately saline. It grows in precipitation zones of 6 to 20 inches (optimum 12 to 14 inches) at elevations ranging from 2,000 to 7,500 feet. It prefers dry, well-drained areas, but responds to additional moisture, and can withstand considerable periodic flooding. The early emergence and good seedling vigor of this plant make it well adapted to erosion control on drastically-disturbed sites, i.e., roadsides, oil and gas well sites, coal mines, urban development, etc.

Limitations

Once established, the stands thicken and tend to become unproductive. It is less productive than western wheatgrass or most of the introduced, drought-tolerant grasses. It is competitive with weeds and other native species, but is easily crowded out by such introduced species as crested wheatgrass and smooth bromegrass.

Use for Hay

Thickspike wheatgrass produces a palatable and nutritious hay, although it is more productive when utilized as pasture. In early May, the protein level is about 20 percent, decreasing to about four percent in October. The digestible carbohydrates remain at about 45 percent throughout the growing season. Yields of hay depend greatly on the amount of extra moisture a site may receive. Native harvests will generally be made from stands composed of thickspike in association with western wheatgrass and/or green needlegrass.

Use for Pasture

It is palatable to all grazing animals, both domestic and wild. It starts growth early in the spring, and provides good grazing until early fall when it becomes somewhat wiry. Although it can be seeded alone, it is usually included in a broader mixture. The long, creeping rhizomes enable thickspike wheatgrass to withstand heavy grazing and considerable trampling. Once established, this grass will continue to spread and thicken the stand if conservatively grazed. It is quite compatible with western wheatgrass, as neither one forms a very tight sod under dryland conditions.

Seed Production

Seed production has been excellent, averaging 350 to 500 pounds per acre under irrigation at Bridger, Montana, and 200 pounds per acre on dryland at Moccasin, Montana. There has been some problem with slender wheatgrass-type plants developing in thickspike wheatgrass seed production fields. The Bridger Plant Materials Center has made efforts to reduce these off-types in the breeder and foundation seed, and the Montana Seed Growers Association has made adjustments in the standards to allow for this problem. Although this is a strongly rhizomatous species, most seed fields are maintained in rows. Seed fields are only productive for two or three crops. Harvesting of this crop is best done by swathing, followed by combining of the cured windrows. Seed is generally harvested in mid-July.

* 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.