NOTICE OF RELEASE OF `RIMROCK' INDIAN RICEGRASS

J. G. Scheetz, M. F. Majerus, T. A. Jones, and L. K. Holzworth

The Plant Science Division, Natural Resources Conservation Service, U.S. Department of Agriculture, the Agricultural Experiment Stations of Montana and Wyoming, and the USDA Agricultural Research Service announce the release of `Rimrock' Indian ricegrass [Oryzopsis hymenoides (Roem. and Schult.) Ricker ex Piper]. This grass was developed by the USDA-NRCS Plant Materials Center at Bridger, Montana.

Rimrock was collected in 1960 from a native sandy range site (elev. 1,101 meters) one kilometer north of Billing, Montana. The area receives 250-350 mm of annual precipitation. Rimrock is predominantly self-pollinated and not limited by self-incompatibility. Rimrock was tested as M-33, P-15597, T-05424, 9005424, and PI-478833, compared to 82 other accessions of Indian ricegrass, and directly increased without selection. Rimrock is a perennial, cool-season bunchgrass found on soils that are neutral to mildly alkaline, with low water holding capacity, low clay content, high bulk density, and with few rock fragments. The distribution of this grass ranges from the Nebraska sand hills west to the eastern slopes of the Cascade and Sierra-Nevada range, and from Mexico to Canada at elevations up to 3,000 meters. Rimrock is a native grass that can be used in seed mixtures for range revegetation and reclamation of disturbed sandy soils. Rimrock produces an abundance of plump seed with protein levels of 15 to 17 percent. This seed is excellent food for upland game birds and songbirds. This grass can be planted with or adjacent to taller plant for food and cover for a wide variety of wildlife. Rimrock was released primarily because of its ability to retain mature seed better than the cultivars Paloma (origin Pueblo, CO) or Nezpar (origin Idaho). The more acute angle of the glume of Rimrock helps retain seed longer and protects from catastrophic shattering events such as high winds and heavy rain.

Foundation seed is available from USDA- RCS at Bozeman, MT 59715-4704.