ALPINE VASCULAR FLORA OF THE TUSHAR MOUNTAINS, UTAH

The Tushar Mountains of southwestern Utah rise to a maximum elevation of 3709 m, with tinlberline and krummholz reaching maximum elevations of 3438 m and 3566 m, respectively. Voucher specimens were collected from the alpine region during eight field seasons to inventory this largely unknown alpine flora. Listed are 171 vascular plant species from 102 genera and 34 families that occur in eight types of plant communities within an alpine area of about 19.3 km(3). The seven largest families are Asteraceae (29 species), Poaceae (20), Brassicaceae (13), Rosaceae (12), Cyperaceae (11), Carpophyllaceae (10), and Fabaceae (8). Thirteen species are restricted to the alpine area. The perennial herb growth form accounts for 86.4% of the flora, 5.9% of the species are shrubs, and the remaining species are annuals to short-lived perennials. Bedrock in the alpine region is entirely of Tertiary igneous origin. Vegetation cover and species richness are highest on an andesite ash-flow tuff and latite flow and lowest on hydrothermally altered inter-caldera rhyolites and tuffs. Forty-four species (26.0% of the indigenous flora) also occur in the Arctic, and 13 species are at a southern margin of distribution. Eight taxa (4.7% of the nora) are local or regional endemics. The majority of the alpine species appear to have migrated to the range by way of the contiguous mountain system to the north; statistical comparison with neighboring alpine floras shows the flora to be most similar to the floras of the Wasatch Mountains, Uinta Mountains, and Teton Range, with Sorensen's similarity indices of 52.8, 50.2, and 48.8% respectively.