Taxonomy in this genus currently follows three conflicting treatments: CNPS (Kearney), Jepson 2nd Edition, and Flora of North America. I am currently working on resolving the taxonomy with molecular and morphological approaches. In the meantime, I am following the most conservative treatment (Kearney) which is mostly followed by CNPS. This treatment best fits my current hypothesis on taxon delimitation and retains CNPS listed rare taxa that the other treatments lump.