Caulanthus coulteri is a species of flowering plant in the mustard family known by the common name Coulter's wild cabbage. It is endemic to California, where it is a widespread member of the flora in several dry, open habitat types, such as chaparral and Mojave Desert. Caulanthus coulteri is an annual herb producing a slender, branching stem lined with generally lance-shaped leaves which may be smooth to sharply sawtoothed along the edges. The widely spaced flowers are somewhat bullet-shaped with coats of pouched sepals which are bright to deep purple when new and fade to yellow-green. The sepals open to reveal dark-veined petal tips with wavy margins. The fruit is a long, thin silique which may approach 13 centimeters in length.