Plant Species: Pseudoroegneria spicata, bluebunch wheatgrass
Kingdom: Plantae
Phylum: Magnoliophyta -- flowering plants
Class: Liliopsida -- monocots
Family: Poaceae (Gramineae) -- grass
Genus: Pseudoroegneria
Species: spicata
Variety:
Common Name: bluebunch wheatgrass, beardless wheatgrass
Species Code: PSSP6, PSSPI, PSSPS
Origin: Native to arid and semi-arid portions of the western US and Canada east to Montana and south to Texas, except California and Arizona, where mean annual precipitation ranges from 10-35 inches.
Rare: no
Form: bunchgrass
There are both awned and unawned forms. The unawned forms are sometimes referred to P. spicata ssp. inermis and the awned forms are then called P. spicata ssp. spicata. Both forms are sometimes found on the same site.
Duration: perennial
Longevity: long
Habitat Type: prairie, shrub thickets, forest
Wetland Indicator Status: UPL
Leaves: Leaves are evenly distributed with open sheaths and well developed auricles, membranous ligules, and the blades flat or somewhat involute.
Mature height: 0.4 to 1 meter
Flowers: Flowers are inconspicuous except when the anthers are expressed. Florets are perfect. The inflorescence is an erect, terminal spike with 1 spikelet per node. Spikelets are slightly to twice as long as the internodes and tightly appressed. Awns, when present, are strongly divergent.
Flower color:
Bloom: June
Bloom starts on: June
Bloom ends on: June
Fruit: Fruit is a caryopsis.
135,000-150,000 seeds/lb for A. inerme (Hassell et al 1996).
95,000-150,000 seeds/lb for A. spicatum (Hassell et al 1996).
Vegetation type:
Characteristics:
Pseudoroegneria spicata is the preferred name. Agropyron spicatum and A. inerme are synonymous.
Most plants only reproduce sexually by seed but the plants on deep soils of the Palouse have short rhizomes and also reproduce vegetatively.
Fibrous rooted.
2n=14.
Triploids, tetraploids, octoploids are also known (Hitchcock et al 1969).
Almost all species in Pseudoroegneria are diploids or autotetraploids (Carlson 2006).
Primarily wind pollinated.
Apomixis has not been reported, but Marchand & McLean (1965) reported vegetative proliferation of plantlets (sometimes referred to as vivipary) in the inflorescence of fall regrowth, probably caused by environmental conditions. They speculated that it might be day-length related.
Obligately xenogamous (Carlson 2006). Can self pollinate, but seed production is greatly reduced (Smith 1944).
The plants are excellent forage for livestock and wildlife, but do not tolerate close grazing. Rodents eat the seeds and feed on the crowns, especially in winter.
Many grasses are hosts for the larva of the common wood nymph (Cercyonis pegala) and the common ringlet (Coenonympha californica) butterflies (Pocewicz 2005).
Comments: St. John (1963), Piper & Beattie (1914), and Davis (1953) all recognized both A. spicatum and A. spicatum var. inerme. The awnless phase was sometimes recognized as a separate species, A. inerme, by other authors.
Elytrigia spicata is synonymous.
Several cultivars have been released, including "Goldar", "Anatone", "P-7", and "Whitmar" (an awnless form, but without rhizomes).
The cultivar “Secar” was released as P. spicata, but was later determined to be a previously unrecognized species, Elymus wawawaiensis (Carlson & Barkworth 1997).
Sun requirement: full
Soil moisture: xeric to mesic
Precipitation: 10-35 inches
Fire: Regenerates after fire by seed germination and some sprouts from surviving growing points. Usually not seriously damaged by fire. Response depends on severity of fire and physiological state of plant. Damage will be greatest following dry year (Patterson et al 1985).
Hazards:
Sowing time: spring
Transplant time: spring
Stratification: not required
Seed yield: 100-200 lbs/acre
Seed harvest: mid to late July
Seed first harvest: second full growing season
Seed cleaning: properly deawned seed is relatively easy to clean.
Planting duration: seed production declines after the fourth or fifth harvest.
Seed insect problem: none noted
Seed shatter: increases with maturity.
Seed size: large
Seed harvest date: mid to late July
Seed comments:
Herbaria:
Key words:
Alternate Genus: Agropyron
Alternate Species: spicatum
Alternate Variety:
Propagation:
There are a bunch of protocols in the
Native Plant Network propagation protocol database (some with rather creative spellings).
Other Propagation Information:
Bluebunch wheatgrass can be grown in the greenhouse for plugs or seeded directly in the ground. Spring seedings are more likely to be successful on the Palouse. Fall seedings are prone to stand failure due to winter kill and frost heaving. Seeds are easy to germinate and need no stratification.
In areas receiving less than 16 inches mean annual precipitation, seedings should be made in the late fall or winter.
Seed germinates at a wide range of temperatures. Some seeds may have a short after-ripening period (1 month), but other seed does not. Can germinate in high temperatures of late summer (Young et al 1981).
In the field, seeds germinate mainly in the fall (Harris 1967).
There is no correlation between current season inflorescence production and climate data from the previous season (Daubenmire 1978).
Most plants only reproduce sexually by seed but the plants on deep soils of the Palouse have short rhizomes and also reproduce vegetatively.
Notes:
References:
Carlson, Jack R.
Pseudoroegneria (Nevski) Á. Löve. In: Manual of Grasses for North America. Intermountain Herbarium, Utah State University, Logan Utah. Online at http://www.herbarium.usu.edu/webmanual/ Accessed 11/6/06.
Carlson, Jack R., and Mary E. Barkworth. 1997. Elymus wawawaiensis: A species hitherto confused with Pseudoroegneria spicata (Triticeae, Poaceae). Phytologia 83:312-320.
Collins, D., and T. Weaver. 1978. Effects of Summer Weather Modification (Irrigation) in Festuca idahoensis-Agropyron spicatum Grassland. Journal of Range Management 31:264-269.
Cui, M., and M.M. Caldwell. 1997. Growth and Nitrogen Uptake by Agropyron desertorum and Pseudoroegneria spicata when Exposed to Nitrate Pulses of Different Duration. Australian Journal of Plant Physiology 24:637-642.
Daubenmire, R.F. 1939. The Taxonomy and Ecology of Agropyron spicatum and A. inerme. Bull. of the Torr. Bot. Club 66:327-329.
Daubenmire, R.F. 1960. An Experimental Study of Variation in the Agropyron spicatum-A. inerme Complex. Botanical Gazette 122:104-108.
Daubenmire, R.F. 1978. Annual Variation in the Flowering of Agropyron spicatum Near Clarkston, Washington. Northwest Science 52:153-155.
Davis, Ray J. 1952. Flora of Idaho. Wm. C. Brown, Dubuque, Iowa. 827 pp.
DeWitt, Floyd P. 1969. Early Developmental Response to Low Temperature in Agropyron spicatum Collected from Native Stands in Western North America. MS Thesis (Agronomy) Washington State University.
Harris, Grant A. 1967. Some Competitive Relationships Between Agropyron spicatum and Bromus tectorum. Ecological Monographs 37:89-111.
Hassell, Wendell, W. Rocky Beavers, Steve Ouellette, and Thomas Mitchell. 1996. Seeding Rate Statistics for Native and Introduced Species. US Dept of Interior and USDA, NRCS. Denver, CO.
Heady, Harold F. 1950. Studies on Bluebunch Wheatgrasses in Montana and Height-Weight Relationships of Certain Range Grasses. Ecological Monographs 20:55-81.
Hitchcock, C. Leo, Arthur Cronquist, Marion Ownbey, and J.W. Thompson. 1969. Vascular Plants of the Pacific Northwest. University of Washington Press. Seattle, WA. 5 vol.
Marchand, L.S. and A. McLean. 1965. Observations on the Vegetative Proliferation in Agropyron spicatum. Canadian Journal of Botany 43:1533-1537.
Patterson, Patricia A., Kenneth E. Neiman, and Jonalea R. Tonn. 1985. Field Guide to Forest Plants of Northern Idaho. USDA Forest Service Intermountain Research Station. General Technical Report INT-180. Ogden, Utah.
Piper, C.V., and R.K. Beattie. 1914. The Flora of Southeastern Washington and Adjacent Idaho. Lancaster, PA: Press of the New Era Printing Company. 296 pp.
Pocewicz, Amy. 2005. Host Plants of Palouse Butterfly Species. 2 page handout to accompany the April 2005 presentation to the Palouse Prairie Foundation.
Pyke, David A. 1986. Demographic Responses of Bromus tectorum and Seedlings of Agropyron spicatum to Grazing by Small Mammals: Occurrence and Severity of Grazing. Journal of Ecology 74:739-754.
Pyke, David A. 1987. Demographic Responses of Bromus tectorum and Seedlings of Agropyron spicatum to Grazing by Small Mammals: the Influence of Grazing Frequency and Plant Age. Journal of Ecology 75:825-835.
Sedivec, Kevin K., and William T. Barker. 1998. Selected North Dakota and Minnesota Range Plants. North Dakota State University Department of Animal and Range Sciences Extension Bulletin EB-69. Fargo, North Dakota. Accessed 12/10/06 online at http://www.ag.ndsu.edu/pubs/ansci/range/eb69-2.htm
Smith, D.C. 1944. Pollination and Seed Formation in Grasses. Journal of Agricultural Research 68:79-95.
Young, J.A., R.F. Eckert, Jr., and R.A. Evans. 1981. Temperature Profiles for Germination of Bluebunch and Beardless Wheatgrasses. Journal of Range Management. 34:84-89.