Caulanthus hallii is an annual herb producing a hollow stem fringed at the base with long, deeply cut leaves which are hairless or sometimes bristly.
The greenish-yellow flower has a coat of hairy sepals over narrow, pale petals. The fruit is a silique up to about 11 centimeters long.
It is native to southern California and northern Baja California.
It grows in the Colorado Desert (western Sonoran Desert), Mojave Desert sky islands, and the dry eastern Peninsular Ranges slopes.