Brassica tournefortii
29 Palms Hwy (62) W of
jct. with Hwy 177, CA, Mar. 2005.
A weed that completely covers the ground over extensive areas of the
southern Mojave Desert. 

See also http://www.unce.unr.edu/publications/FS05/FS0502.pdf

Brassica tournefortii

Red Cloud Rd, Chuckwalla Mts., CA
Mar 2005