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Montana Field Guide

Montana Field Guides

Contracted Indian Ricegrass - Oryzopsis contracta
Other Names:  Achnatherum contractum, Oryzopsis hymenoides var. contracta

Status Under Review

Global Rank: G3G4
State Rank: S3?

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value:

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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.

Species Range
Present
 


Range Comments
Regional endemic; throughout much of WY, southwestern MT, Daggett County, UT, and Jackson County, CO (Kartesz in prep. 2012).

Summary of Observations Submitted for Montana
Number of Observations: 6

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
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.

References
  • Additional ReferencesLegend:   View Online Publication
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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 Unpublished report to Bureau of Land Management.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 Unpublished report to the Bureau of Land Management.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.
    • 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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Citation for data on this website:
Contracted Indian Ricegrass — Oryzopsis contracta.  Montana Field Guide.  .  Retrieved on , from