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Contracted Indian Ricegrass - Oryzopsis contracta
Other Names:
Achnatherum contractum, Oryzopsis hymenoides var. contracta
General Description
Contracted Indian ricegrass is a tufted perennial with glabrous stems 30-64 cm (12-28 in) tall. The infloresence is a panicle with branches that are intially contracted, hence the common name, but which become stiffly spreading at maturity. Spikelets are single flowered, slender, and 1.5 cm (3/4 in) long. Each hardened narrowly elliptic spikelet, 5-7 mm long, has 2 glumes enclosing the short-hairy lemma with an awn, 6-12 mm long.
Phenology
Single specimen collected on July 15, flowering presumed.
Diagnostic Characteristics
Oryzopsis contracta could easily be confused with the common Indian ricegrass, O. hymenoides. However, the latter has a more egg-shaped spikelet, shorter awns, 3-8 mm long, and the hairs of the lemma extend well beyond its apex.
Range Comments
Regional endemic; throughout much of WY, southwestern MT, Daggett County, UT, and Jackson County, CO (Kartesz in prep. 2012).
Observations in Montana Natural Heritage Program Database
Number of Observations: 9
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Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Sandy or gravelly soil of grasslands and sagebrush steppe in the valleys and montane zone.
Stewardship Responsibility
References
- Additional ReferencesLegend:
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Fertig, W. 1994. Status report on Oryzopsis contracta, a USFWS Category 2 candidate species. Unpublished report to Bureau of Land Management. Wyoming Natural Diversity Database, Laramie. 41 pp.- Heidel, B. L. 1996. Noteworthy collections - Montana. Madrono 43(3):436-440.
- Heidel, B.L. and J. Vanderhorst. 1996. Sensitive plant species surveys in the Butte District, Beaverhead and Madison Counties. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, Montana.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
- Vanderhorst, J., B.L. Heidel, J. Pierce, and S.V. Cooper. 1997. Botanical survey of the Ruby Range, Madison County, Montana. Unpublished report to the Bureau of Land Management Dillon Resource Area. Montana Natural Heritage Program, Helena, MT. 47. pp. plus appendices.
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