The alpine zone of the Sierra Nevada of California, defined as non-forested areas at or above 3500 m, includes 385 species (409 taxa) of native vascular plants. Were the alpine boundary defined as at or above 3300 m, the alpine flora would grow to 536 species (570 taxa). There are 97 species that reach elevations of 4000 m and 27 species that reach to 4200 m. Over half of the alpine species occur in just six families, led by the Asteraceae (55 species, 59 taxa), Poaceae (39 species, 47 taxa), Brassicaceae (34 species), and Cyperaceae (31 species). The largest genus present is Carex with 29 species, and 18 more species would be added by lowering the alpine boundary to 3300 m. Next in size are Draba (14 species) and Lupinus (11 species, 16 taxa). Life forms of the flora are heavily dominated by broad-leaved erect perennials (50%), followed in importance by graminoid perennials (21%) and mats and cushions (11%). Annuals and woody shrubs each account for about 6% of the flora. Only nine species are obligate alpine taxa with a range restricted to elevations of 3500 m or above. An additional 67 species (17% of the flora) occur in both subalpine and alpine habitats but not lower. More than a quarter of the alpine species have elevational ranges that extend as low as foothill habitats defined as occurring below 1200 m. In terms of biogeographic affinities, the broad relationships of the flora include the cordillera of western North America (35%), Intermountain region of the Great Basin (20%), Sierra/Cascade axis (16%), and widespread distributions (14%). There are 36 species in the alpine flora endemic to the Sierra Nevada, and another 31 species that are Californian endemics.