 This species once included several other species of "Thermopsis", but in 1994, the others were separated out and elevated to species status, and the name "T. macrophylla" was applied to this rare variety limited to the Santa Ynez Mountains.This is a rhizomatous perennial herb growing up to tall and wide.It produces up to ten inflorescences each bearing up to 100 bright yellow flowers up to long each.