Perennial Ryegrass - USDA Plants Database

SNAKE RIVER 

WHEATGRASS 

Elymus wawawaiensis 

J. Carlson & M. Barkworth 

Plant Symbol = ELWA2 

Contributed by: USDA NRCS Idaho State Office 

Snake River Wheatgrass. Dr. Tom Jones, USDA, ARS, Logan, UT 

Alternate Names 

Formerly referred to as bluebunch wheatgrass before the 

description of Snake River wheatgrass as a new species. 

Uses 

Grazing/rangeland/wildlife: Snake River wheatgrass is 

palatable to all classes of livestock and wildlife. It is a 

preferred feed for cattle, horses, sheep, elk, deer and 

antelope in spring when protein levels can be as high as 

20 percent. Protein levels decrease to about 4 percent as 

the grass matures and cures by early to mid summer. 

Digestible carbohydrates remain about 45 percent 

throughout the active growth period. 

Erosion control/reclamation: Snake River wheatgrass is 

very drought tolerant, stands are persistent once 

established, and it is adapted to stabilization of disturbed 

soils. It is very compatible with slower developing 

natives such as streambank wheatgrass, thickspike 

wheatgrass, basin wildrye, western wheatgrass, bluegrass 

Plant Guide 

species, and needlegrass species. It does not compete 

well with aggressive introduced grasses. Its drought 

tolerance, combined with an extensive root system and 

fair to good seedling vigor, make this species ideal for 

reclamation in areas receiving 10 to 20 inches annual 

precipitation. The cultivars ‘Discovery’ and 'Secar' 

compete well in areas as low as 8 inches annual rainfall. 

This grass can be used in urban areas where irrigation 

water is limited to stabilize ditch banks, dikes, and 

roadsides as a component of a native mix. 

Description 

General: The natural distribution of Snake River 

wheatgrass is limited to eastern Oregon, eastern 

Washington, and west central to northern Idaho, but it is 

widely used as a surrogate for bluebunch wheatgrass for 

restoration, reclamation, and rehabilitation of rangelands 

in the Columbia Plateau, Northern Basin and Range, 

Central Basin and Range, and Snake River Plain, which 

encompass large portions of eastern Washington, eastern 

Oregon, southern Idaho, Nevada, and western Utah. 

Snake River wheatgrass is a long-lived, perennial, coolseason 

native bunchgrass with an extensive root system 

with strong tillers. Snake River wheatgrass spreads by 

seed. 

Snake River wheatgrass can be morphologically 

distinguished from bluebunch wheatgrass by characters 

such as the ratio of spikelet length to internode length, 

glume shape, seedling pubescence, and seedling leaf 

marginal barbs (Jones et al., 1991). 

Snake River (left) vs. awned (center) and awnless( right) bluebunch 

wheatgrasses 

Snake River wheatgrass has a seed of considerably 

smaller mass than bluebunch wheatgrass. Snake River

wheatgrass is always awned, while bluebunch wheatgrass 

may be awned or awnless. Snake River wheatgrass is 

always allotetraploid (2n=28) while bluebunch 

wheatgrass may be diploid (2n=14) or autotetraploid 

(2n=28) (Carlson and Barkworth, 1997). 

Adaptation and Distribution 

Snake River wheatgrass does best on medium to coarsetextured 

soils, but can be found on heavy to medium to 

coarse-textured soils over 10 inches deep, including fairly 

sandy sites. It can be seeded on clayey sites. It may be 

found on thin, rocky sites and on very steep slopes. It 

tolerates weakly saline conditions. It does not grow on 

acidic sites. It is cold tolerant, moderately shade tolerant, 

and very tolerant of fire. It is intolerant of high water 

tables, poor drainage, and periods of extended inundation. 

On native sites Snake River wheatgrass is most abundant 

in the 8 to 20 inch annual precipitation zones. When 

seeded, it does best with 10 to 20 inches of precipitation 

(‘Discovery’ and 'Secar' have established with as little as 

7 inches) and it will tolerate up to 35 inches on very welldrained 

soils. The elevation range is from 500 feet above 

sea level to 10,000 feet. It is a major component of native 

plant communities where it is found and generally 

occupies 20 to 60 percent of the overall composition by 

weight of the plant community. 

For a current distribution map, consult the Plant Profile 

page for this species on the PLANTS Website. 

Status 

Consult the PLANTS Website and your State Department 

of Natural Resources for this plant’s current status (e.g. 

threatened or endangered species, state noxious status, 

and wetland indicator values). 

Establishment 

This species should be seeded with a drill at a depth of 1/2 

inch or less on medium-textured soils, 1/4 inch on finetextured 

soils and 3/4 inch or less on coarse-textured soils. 

The single species seeding rate recommended for this 

grass is 8 pounds Pure Live Seed (PLS) or about 24 PLS 

per square foot. If used as a component of a mix, adjust 

to percent of mix desired. For broadcast plantings, mined 

lands, and other harsh critical areas, the seeding rate 

should be increased to 40 to 50 PLS per square foot. 

Seedlings are significantly weaker than crested 

wheatgrass and a clean firm weed free seedbed is required 

for establishment (cheatgrass and other weed competition 

can cause stand failure). 

Seed in very early spring on heavy to medium- textured 

soils and in late fall on medium to light- textured soils. 

Late summer (August to mid- September) seeding is not 

recommended unless irrigation is available. Dormant fall 

seedings will pre-chill seed and improve germination. 

Snake River wheatgrass establishes fairly quickly for a 

native grass and stands should be given up to 3 years to 

ensure establishment. It is compatible with other native 

species and should be used in seeding mixtures. It should 

not be seeded with strongly competitive introduced 

species. 

Stands may require weed-control measures during 

establishment. Application of 2,4-D should not be made 

until plants have reached the four to six-leaf stage. Mow 

weeds at or prior to their bloom stage. New stands may be 

damaged by grasshoppers and other insects and pesticides 

may be needed. 

Management 

Stands of Snake River wheatgrass should not be grazed 

until they have firmly established (usually two to three 

growing seasons) and started to flower. 

Six inches of new growth should be attained in spring 

before grazing is allowed in established stands. The 

growing point of Snake River wheatgrass is fairly high 

and stands can be easily overgrazed. Spring grazing 

should occur no more than one out of three years and no 

more than 40 percent utilization should occur during rapid 

growth. Heavy early-spring grazing is especially 

damaging, and grazing should be delayed until flowers 

are halfway emerging from the protecting leaf. No more 

than 60 percent utilization should occur after seed ripens. 

Snake River wheatgrass is not suited to hay production 

and is best suited to rangeland, critical area stabilization, 

and cropland retirement type uses. 

Environmental Concerns 

Snake River wheatgrass is long lived and spreads 

primarily via seed distribution. It is not considered a 

"weedy" or invasive species, but can spread into adjoining 

vegetative communities under ideal climatic and 

environmental conditions. Most seedings do not spread 

from original plantings. 

It is a cross-pollinating species and is known to cross with 

bluebunch wheatgrass, thickspike wheatgrass, quackgrass, 

and bottlebrush squirreltail. These interspecific hybrids 

generally exhibit low fertility and do not dominate a site 

or crowd out non-hybrid plants. 

Seed Production 

Seed production of Snake River wheatgrass has been very 

successful under cultivated conditions. Row spacing of 

24 to 36 inches are recommended under irrigation and 36 

inches under dryland conditions. Seeding rates of 3 to 4 

PLS per acre are recommended. Cultivation and/or 

judicious use of appropriate herbicides will be needed to 

maintain rows and weed-free conditions. 

Seed fields are productive for three to four years. 

Average production of 75 to 100 pounds per acre can be 

expected under dryland conditions. Average production

of 250-500 pounds per acre can be expected under 

irrigated conditions. 

A Snake River wheatgrass seed production field 

Dr. Tom Jones, USDA, ARS, Logan, UT 

Harvesting is best completed by swathing, followed by 

combining of the cured rows. The seed heads readily 

shatter and require close scrutiny of maturing stands. If 

direct combined, harvest at 30 percent moisture and dry 

seed down to 12 percent moisture (if stored in bins) or 15 

percent moisture (if stored in sacks). 

Debearding will be required during processing. Seed is 

generally harvested from mid-July to mid-August. 

Cultivars, Improved, and Selected Materials (and area 

of origin) 

‘Discovery’, the second Snake River wheatgrass (Elymus 

wawawaiensis) plant material, was released in 2008 

(Jones, 2008). It was developed from four accessions that 

were found to have improved vigor in comparison to 

Secar. These accessions were crossed and seed was 

harvested in bulk to generate Discovery. 

Discovery was compared to Secar in seeded trials at two 

sites in the Intermountain Region and four sites in the 

Great Plains (Jones, 2008). Stand frequency of Discovery 

in the Intermountain locations for year 2 was 49.3% 

compared to 27.4% for Secar. Forage yield of Discovery 

for years 2 to 4 was 108.0% greater than Secar. No 

significant differences were observed at the Great Plains 

locations. Discovery was also compared to Secar in a 

transplanted trial at Millville, Utah where it produced 

18% greater straw weight across two densities the 

summer after establishment. 

The populations used to generate Discovery trace to 

materials collected in Whitman and Asotin counties in 

southeastern Washington and Idaho County in central 

Idaho. 

Breeder seed is maintained by the USDA-ARS Forage 

and Range Research Laboratory, Logan, UT, and will be 

made available to commercial growers through the Utah 

Crop Improvement Association for production of 

Foundation, Registered, and Certified generations. 

'Secar' is the original cultivar release of Snake River 

wheatgrass (Elymus wawawaiensis). It was originally 

released as a bluebunch wheatgrass, but cytological 

examination later determined it to be Snake River 

wheatgrass. The original collection site for Secar is along 

the Snake River Gorge near Lewiston, Idaho. The Idaho- 

Oregon- Montana-Wyoming AES, Washington 

Agriculture Research Center, and Pullman Plant Materials 

Center released Secar in 1980. 

It is one of the most drought-tolerant native perennial 

grasses available and can survive down to 8 inches 

rainfall. It is a bunchgrass with fair to good seedling vigor 

and establishes well under droughty conditions. While 

Secar is considered to be highly drought tolerant as a 

mature plant, drought often reduces the stand during the 

establishment year. 'Secar' is intended for use on 

rangeland for re-establishment of native-plant 

communities and for cropland retirement type plantings. 

Certified seed is available and Breeder seed is maintained 

by Pullman PMC. Foundation seed is available through 

the Washington State Crop Improvement Association. 

References 

Alderson, J. & W.C. Sharp 1994. Grass varieties in the 

United States. Agriculture Handbook No. 170. 

USDA, SCS, Washington, D.C. 

Carlson, J.R. & M.E. Barkworth 1997. Elymus 

wawawaiensis: a species hitherto confused with 

Pseudoroegneria spicata (Triticeae, Poaceae). 

Phytologia 83:312-330. 

Cronquist, A., A.H. Holmgren, N.H. Holmgren, J.L. 

Reveal, & P. K. Holmgren 1977. Intermountain 

Flora. Vol. 6. The New York Botanical Garden. 

Columbia University Press, New York, New York. 

Hitchcock, A. S. 1950. Manual of the grasses of the 

United States. USDA, Washington, DC. 

Jones, T.A. 2008. Notice of release of ‘Discovery’ Snake 

River wheatgrass. Native Plants J. 9:99-102. 

Jones, T.A., D.C. Nielson, and J.R. Carlson. 1991. 

Developing a grazing-tolerant native grass for 

bluebunch wheatgrass sites. Rangelands 13:147-150. 

Miller, R.P., J.M. Seufert, and M.R. Haferkamp. 1987. 

The ecology and management of bluebunch 

wheatgrass (Agropyron spicatum): A review. Oregon 

Agric. Exp. Sta. Bull. No. 669.

Morrison, K.J., and C.A. Kelley. 1981. Secar bluebunch 

wheatgrass. EB 0991. Cooperative Extension, 

Washington State University, Pullman. 

USDA, Forest Service 1996. Fire effects information 

system. Version: 000413. Rocky Mountain Research 

Station, Fire Sciences Laboratory, Missoula, MT. 

http://www.fs.fed.us/database/feis/ 

USDA, NRCS 2000. The PLANTS database. 

http://plants.usda.gov National Plant Data Center, 

Baton Rouge, Louisiana. 

Prepared By 

Daniel G. Ogle 

USDA, NRCS, Idaho State Office, Boise, Idaho 

Mark Stannard 

USDA, NRCS, Plant Materials Center, Pullman, 

Washington 

Dr. Thomas A. Jones 

USDA, ARS, Forage and Range Laboratory, Logan, Utah 

Species Coordinator 

Daniel G. Ogle 

USDA, NRCS, Idaho State Office, Boise, Idaho 

Published September 2008 

Edited: 091608dgo; 091508ms; 071108taj 

For more information about this and other plants, please 

contact your local NRCS field office or Conservation 

District at http://www.nrcs.usda.gov/ and visit the 

PLANTS Web site at http://plants.usda.gov/ or the Plant 

Materials Program Web site http://plantmaterials.nrcs.usda.gov. 

PLANTS is not responsible for the content or availability 

of other Web sites. 

USDA IS AN EQUAL OPPORTUNITY PROVIDER AND EMPLOYER

Perennial Ryegrass - USDA Plants Database

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