Ceanothus thyrsiflorus can grow more than 6 metres (20 feet) tall and broad in its native chaparral habitat, with glossy green leaves.

The clusters of tiny flowers, borne in spring, vary from different shades of blue to close to white.

[3] The Latin genus name Ceanothus is derived from the Ancient Greek, keanothos (κεάνωθος; 'spiny plant').

The name was originally used by Theophrastus for another plant, and Linnaeus reused it for Ceanothus.

[4] The Latin specific epithet thyrsiflorus is derived from the Ancient Greek thyrsos (θύρσος; meaning a 'contracted panicle, wreath, or thyrsos') and the Latin florum (gen. 'flower'), and so, thyrsiflorus means approximately 'with flowers arranged in the shape of a contracted panicle or thyrsos staff'.