Vascular Flora of the Upper Rock Creek Watershed, Eastern Sierra Nevada, California

The upper Rock Creek watershed is located on the east slope of the Sierra Nevada in Inyo and Mono counties. It is ca. 36.5 square miles (94.5 square km) in area and varies in elevation from 7360 to 13,750 ft (2243 to 4191m). Quaternary glacial erosion and deposition produced striking landscape features, including alpine fellfields and numerous small lakes. Previous floristic inventories in Rock Creek recorded a combined 396 minimum-rank taxa (species, subspecies, varieties, named hybrids) but were restricted to Little Lakes Valley and the surrounding high areas. An updated, annotated checklist of vascular plants is presented, based on preexisting specimens and new collections. I conducted intensive fieldwork from 2012 through 2016, resulting in 1506 collections (including two collections from a brief 2018 visit). More than 1000 historical collections were examined. The resulting checklist contains 591 taxa, of which 25 (4.2%) are nonnative to California and 32 (5.4%) are special-status plants. My fieldwork resulted in 128 taxa previously undocumented for the watershed. Eighty-one species historically collected were not rediscovered and are noted as such in the checklist. Nine taxa are new county records. The flora is represented by 77 families, 248 genera and 572 species. For each taxon, the checklist cites at least one collection and indicates the vegetation type(s) where it has been documented and its abundance in the watershed. A brief review of botanical exploration in the watershed during the past century is presented, along with geology, climate, vegetation and history of human activity.