In years past CA botanists referred to this species as Orobanche fasciculata...which was actually a variable complex of plants with many color-forms and many associated host plants, ranging widely throughout the western US and east to Michigan. In late 2016 the species was moved into the resurrected genus Aphyllon (see Schneider(2016)), and per the revision of the 'A. fasciculatum complex' in Schneider & Benton(2021)...this yellow-flowered form, with corolla lobes apically acute and becoming reddish, and on host plant Eriodictyon californicum (see leaves in background of the photo)...goes to A. franciscanum.