Oryzopsis contracta can be recognized by its contracted or stiffly spreading panicle branches, 

 often with perpendicular pedicel angles, slender-shaped spikelets, and long-awned lemmas with 

 short, silky white hairs. These hairs are equal or less than the length of the lemma (Fertig 1994). 



It was initially described as a variety of Oryzopsis hymejwides (Jolinson 1945) which it most 

 closely resembles. A more detailed study by Shechter and Joluison (1966) led to recognition of 

 this grass as a distinct species. It is intermediate between Oryzopsis hymeiioides and O. 

 micrantha, and is likely to have been overlooked or misidentified in Montana because of its 

 overall resemblance to and habitat overlap with the fonner. Common indian ricegrass {Oryzopsis 

 hymenoides) differs from O. contracta in having a wide-spreading, wavy-branched panicle, 

 plump florets, lemmas with relatively short awns (usually <6 mm), and long silky hairs that 

 exceed the body of the lemma (Wyoming Rare Plant Technical Committee 1994). The pedicel 

 angles of branching are noticeably different in the field, providing a quick basis for making 

 distinctions when matured inflorescences are present. Littleseed ricegrass {Oryzopsis micrantha) 

 is distinguished by having glabrous lemmas and strictly contracted panicle branches. 



Note: Oryzopsis (ricegrass) is a widespread genus represented by five species in Montana. In a 

 recent revision by Bai'kwoilh (1993), it has been split into three genera. By this treatment, 

 Oryzopsis contracta becomes a synonym of Acherantherwn contractmn in a genus which 

 includes most of the former species of Oryzopsis in addition to the short-awned species of Stipa 

 (Fertig 1994). 



GEOGRAPHICAL DISTRIBUTION 



Global distribution: Oryzopsis contracta is a regional endemic of the Rocky Mountains 

 with its center of distribution across central and western Wyoming, extending into north- 

 central Colorado and southwest Montana (Fertig 1994). In 1996, it was also documented 

 from north-central Montana. 



Montana distribution: Oryzopsis contracta is currently known from Beaverhead and 

 Madison Counties in southwestern Montana and from Pondera County in north-central 

 Montana (see state distribution map). It was first recognized as part of the Montana flora 

 when an herbarium specimen deposited at the Rocky Mountain Herbarium in Laramie, 

 WY which had been originally identified as Oryzopsis hymenoides was annotated by 

 Walter Fertig (Wyoming Natural Diversity Database) to O. contracta. The collector, C. 

 W. Griffin, gave the location only as Beaverhead National Forest which at the time of this 

 1921 collection spanned tliree counties. Based on this collection, the species was assigned 

 a state rank of "SH" (known only fi-om historic records in the state). It was later 

 determined that a duplicate of this specimen from Beaverhead National Forest was 

 deposited at MRC. Its collection label included additional location infomiation, 

 mentioning the Sheep Creek Ranger Station. This was interpreted by Peter Stickney to 

 correspond with a site in the Tendoy Mountains, 7 miles west of Lima, in T13S, RIOW, 

 Sec. 36. Five additional sites were documented south of the Pioneer Mountains (Heidel 

 and Vanderhorst 1996). In 1996 it was documented twice in Madison County, during this 

 study and during the separate Spiranthes diluvialis status survey (Heidel in progress). The 

 major range extension documented during a baseline botanical suiTey at Alkali Lake in 

 Pondera County, north-central Montana, is over 300 miles north (Heidel in progress). 



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