Ceanothus americanus is a shrub growing between 18–42 inches high, having many thin branches. Its root system is thick with fibrous root hairs close to the surface, but with stout, burlish, woody roots that reach deep into the earth, root systems may grow very large in the wild, to compensate after repeated exposures to wildfires. White flowers grow in clumpy inflorescenses on lengthy, axillary peduncles. Fruits are dry, dehiscent, seed capsules.