A Vascular Flora of the South Fork Tule River, Southern Sierra Nevada, Tulare County, California

I conducted a floristic study of the South Fork Tule River watershed, located in the southern Sierra Nevada in Tulare County, California. The primary objectives of this floristic study were to document and catalogue all vascular plant taxa that occur in the watershed, describe the plant communities, analyze the flora and its affinities with other areas, and establish a herbarium for the Tule River Indian Reservation. The upper reaches of the South Fork Tule River originate on the western slope of Slate Mountain in the Sequoia National Forest and drain west through the Tule River Indian Reservation into Lake Success. The highest elevation in the watershed is Slate Mountain Peak at 2790 m and the lowest is at Lake Success reservoir, at 162 m. Prior to my study there were only 176 plant collections from the watershed, representing 159 taxa. I spent a total of 64 days over three field seasons (2013–2015) in the study area and made 1356 collections, bringing the total number of minimum-rank taxa to 562, representing 271 genera and 80 plant families. Seven rare taxa were documented during the course of my study, including the federally endangered Clarkia springvillensis. I documented and described 12 plant communities, including giant sequoia (Sequoiadendron giganteum) forests. Several species find their southern extent in the watershed, including the paleoendemic Torreya californica, which occurs on the Tule River Indian Reservation. Floristic affinities analyses revealed that locally, the South Fork of the Tule River does not have many species in common with the North or Middle forks, but this could be a result of collector bias. Statewide, the South Fork has its greatest affinities with the Sierra Nevada Foothills and the Sierra Nevada High eco-geographic subdivisions of California and the least affinity with the desert regions. Poorly documented plant diversity on tribal trust lands speaks to the need for more collaboration with tribal communities, and this flora is a contribution to that effort.