Usually, the two tier taxonomical rank of genus and species is sufficient for botanical classification. Purshia Tridentata Variety Glandulosa, commonly called Desert Bitterbrush, is an example of when an occasional third tier is assigned. The nomenclature can be complex, with some accounts referring to Desert Bitterbrush as a separate species, Purshia Glandulosa.
Keys View of Joshua Tree National Park sits on inclines of the Little San Bernardino Mountains, and their rocky, sandy soils support the native Purshia Tridentata Variety Glandulosa. It drops many drought deciduous, lobed leaves during dry episodes, those which remain curl and shrivel heavily, making identification difficult.
When in bloom, the flowers are white with 5 distinct petals. Throughout the fall months they wilt and fade to shades of orange and brown, which is of diagnostic value. The Genus Purshia, also called Bitterbrush, has approximately 8 accepted species, all endemic to western North America (Canada, US, Mexico). Purshia are known to hybridize with others of the genus. Desert Bitterbrush is believed to be a hybrid between P. Stansburiana and P. Tridentata.
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