orbicular, the lower acuminate, the upper acute, about half the length of the 

 perigynia, reddish- to brownish-yellow with broad hyaline margins and three- 

 ner^'ed, green center; perigynia ascending, broadly ovoid or obovoid, 2.5-3.2 

 mm long, 1.9-2.2 mm wide, obscurely trigonous in cross-section, round- 

 tapering at the base into a broad stipe, puncticulate, glabrous, yellowish-green, 

 strongly many-ribbed (fine), abruptly rounded and depressed at the apex and 

 abruptly short-truncate-beaked; achenes obovoid, trigonous with concave sides, 

 2.5-1.75 mm, substipitate, and short-apiculate (Hermann 1970). 



DIAGNOSTIC CHARACTERISTICS: The most distinguishing character 

 of the species is its inflated perigynia with short, 0.1 to 0.6 mm beaks. It 

 somewhat resembles a very minute watermelon, which tapers slightly towards 

 the base, with a short but obvious beak on top. In addition, the lower bracts are 

 sheathless or nearly so, and the lowest bract is shorter or equal to the length of 

 the inflorescence. Lower spikes are mostly erect, and the terminal spike is 

 entirely staminate (from Hennann 1 970). 



C. GEOGRAPHICAL DISTRIBUTION 



Global Range: Manitoba to Alberta, south to Colorado, South Dakota, and 

 Minnesota. 



State Distribution: An historic collection was made in 1889 from Choteau 

 County, in addition to more recent records from Big Horn, Carter, Powder 

 River, and Rosebud counties (Figure 10). 



Study Area Distribution: This species was documented at 15 locations, 

 widely-scattered, mainly in the northern two-thirds (Figure 1 0). 



D. HABITAT 



ASSOCIATED VEGETATION: Within the study area, Carex torreyi occurs 

 in a variety of sheltered woodland associations (Appendix E-8). It is found 

 most often in drainage bottoms, but is also found on mesic north-facing slopes 

 and their lower benches, and locally in meadow communities bordering woods. 

 The deciduous cover is variable from trace to more often dominant. The trees 

 generally range from 1 5 to 20 cm dbh, and canopy coverage ranges from under 

 20 to ca. 30 percent. Shrub cover ranges from 20 to 50 percent, and consists 

 mostly of low-growing species such as Mahonia repens, Prwius virginiana 

 saplings (less than 0.5 m tall), and Toxicodendron rydbergii. Graminoid cover 

 is usually low, but in one case it is 70 percent. A variety of species includes 

 several species oi Carex, Bromus ciliatus, Poapratensis, and Stipa nelsonii. 

 Forbs range from 1 to 20 percent in cover, and include Galium boreale, 

 Apocynum androsaemifolium, Arenaria lateriflora, and Smilacina stellata. 



37 



