The genus Thermopsis is one of 730 genera in the legume family (Fabaceae), one of the most economically important plant families. Native to North America, including California, Thermopsis is easily recognized and commonly known as “false lupine” for its yellow, lupine-like flowers. Circumscriptions have varied to include anywhere from 4 to 10 species for all of North America and from 1 to 4 in California. In California Thermopsis is infrequent throughout it’s range and most species and subspecies are listed as rare or endangered. Some taxa are represented by unusual disjunct distributions — T californica subsp. argentata implausibly includes similar looking plants restricted to two remote, small regions of completely different geologic origin separated by 885 kilometers with four other Thermopsis taxa occurring in between. Differentiation is based on a few subtle, variable and overlapping quantitative characters that make identifying plants beyond genus difficult.

     Understanding the evolutionary history of species requires a synthesis of many kinds of information. Increasingly, circumscriptions of plant taxa have been reviewed based on a modern understanding of ecological, morphological, biogeographical, and molecular data. Molecular phylogenies, especially, have generated new insights and novel questions about evolutionary relationships. However, many circumscriptions are still based on studies that lack this information. The genus Thermopsis is an example.

References:

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