The common name of caulanthus crassicaulis
refers to the thick stems and dark green, cabbage-like leaves. Stems and leaves are generally hairless, and the stems are usually unbranched. Leaf edges may be entire but typically are deeply lobed, or toothed; leaves grow around the base and at widely-spaced intervals along the stem, where they are much smaller.
Flowers are formed of four pale yellow sepals, up to half an inch long, fused for most of their length, and four brownish or purple petals, which have thin, dry, membranous margins.
Historically, two varieties have been recognized, though the variations are now thought not to be significant. Var crassicaulis
has hairy sepals, purple sepal tips, purple petals and sparsely hairy leaves, while the less common var glaber
has hairless leaves, light brown petals, and sepals which are less hairy, and all-yellow.