G.L. Nesom & G.I. Baird
Pictures of Mojave rubber rabbitbrush are not going to show any differences between this subspecies and threadleaf rubber rabbitbrush (var. oreophila), because the main differences are in subtle characteristics like the length of the involucre. I have searched diligently for definitive discriminants, but most things that differentiate these two sspp. are so variable and with such an overlap in most dimensional ranges as to be almost useless. Ssp. mohavensis is supposed to be often leafless, but I have observed it to be often leafy. The leaves are supposed to be 1-3 cm but I have observed it often to have leaves with a maximum length of 5-6 cm (these on specimens with an involucral length of 11 mm, well beyond that for var. oreophila). The phyllaries are supposed to be sharply angled, but I have seen var. oreophila with equally angled phyllaries. The phyllaries are also supposed to be strongly keeled, but this is an extremely obscure characteristic which does not always seem to be visible even under a microscope. My inclination based on having studied individuals of both of these sspp. all across the San Gabriels is to think that they should never have been made into separate taxa, but they may separate well in other areas. Here mohavensis and oreophila appear to form an intergrading complex, but all of the floras list them as unique taxa, so I am keeping them as separate in this website. Anyway, this is a few-branched perennial shrub growing some 3-8' tall with threadlike leaves (or none). The involucres basically range from 9-12 mm in length and are glabrous. Mojave rubber rabbitbrush is common through dry scrubby environments in the Transverse Range and Mojave Desert, often occupying joshua tree woodland and creosote bush scrub, primarily from about 2500' to 6000', and blooming from September to October. They are particularly prevalent along road edges. These pictures were taken along Mt. Gleason Road in the San Gabriel Mts.
Click here for Latin name derivations: 1) Ericameria