[Wikipedia] Range: Ambrosia dumosa, the burro-weed or white bursage, a North American species of plants in the family Asteraceae. It is a common constituent of the creosote-bush scrub community throughout the Mojave desert of California, Nevada, and Utah and the Sonoran Desert of Arizona and northwestern Mexico (Baja California, Baja California Sur, Sonora, Chihuahua) (contributed by Mary Ann Machi)

[Wikipedia] Dormancy, Allergic Reactions: Ambrosia dumosa becomes dormant during drought, losing all of its leaves to prevent water loss by transpiration; drought deciduous. During this time, it can still be recognized by the presence of longitudinal stripes on smaller stems. Like other types of Ambrosia, this is a ragweed, wind-blown pollen from burro-weed can cause serious allergic reactions. Increasing cases in Mojave Desert as the population grows from Joshua Tree, CA to Las Vegas, NV. (contributed by Mary Ann Machi)