49 



It was initially described as a variety of Oiyzopsis hywenoides (Johnson 1945) which it most closely 

 resembles. A more detailed study by Shechter and Johnson (1966) led to recognition of this grass as a 

 distinct species. It is intemiediate betvseen Oiyzopsis hymenoides and O. micrantha, and is likely to 

 have been overlooked or misidentified in Montana because of its overall resemblance to and habitat 

 ON'erlap with the former. Common Indian ricegrass (Oiyzopsis hymenoides) differs from O. contracta in 

 having a wide-spreading, wa\')'-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 

 Teclinical 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 {Oiyzopsis micrantha) is distinguished by having glabrous lemmas and strictly contracted 

 panicle branches. 



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

 revision by Barkworth (1993), it has been split into three genera. By this treatment, Oiyzopsis contracta 

 becomes a synonym of Acherantherum contr actum in a genus which includes most of the former species 

 of Oiyzopsis in addition to the short-awned species of Stipa (Fertig 1994). 



GEOGRAPHICAL DISTRIBUTION 



Global distribution: Oiyzopsis contracta is a regional endemic of extreme southwestern 

 Montana, central and western Wyoming, and north-central Colorado (Fertig 1994). 



Montana distribution: This species was first recognized as part of the Montana flora when an 

 herbarium specimen deposited in RM that had been originally identified as Oiyzopsis 

 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 spamied tliree counties. Based on this collection, the 

 species was assigned a state rank of "SH" (known only fi-om historic records in the state). After 

 the field season, it was detennined that a duplicate of this specimen fi-om Beaverhead National 

 Forest was deposited at MRC. Its collection label included additional location informafion, 

 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, RlOW, Sec. 36. 

 The five additional sites documented in this study span the Study Area (Figure 21). 



Herbarium specimens in Oiyzopsis hymenoides folders have been checked at MONT (Rumely 

 pers. commun.) and at MONTU (Heidel pers. obs.) without finding additional collections for 

 annotation to O. contracta. Any small herbaria with collections from southwestern Montana 

 should also be checked for misidentified specimens. 



