Dry slopes, Joshua tree and Pinyon-juniper woodland, sagebrush scrub, desert slopes

Ceanothus greggii is a many-branched shrub that grows erect to nearly 2 m (6.6 ft) in maximum height. Its woody parts are gray in color and somewhat woolly. Branches are opposite and rigid.

The evergreen leaves are oppositely arranged, 2 to 9mm long, and variable in shape, with a prominent midvein. They may be toothed or smooth along the edges, and are indeed usually somewhat cupped (see top image).

The inflorescence is a small (less than 2 cm long) cluster of many white flower, on short lateral branches. It blooms in spring. Blooms are considered highly fragrant.

The fruit is a horned capsule a few millimeters wide which bursts explosively to expel the three seeds which require thermal scarification from wildfire before they can germinate.