Ceanothus palmeri (Ceanothus spinosus var palmeri) syn., with the common name Palmer ceanothus, is a species of Ceanothus that is native to southern California and northern Baja California, where it grows in the scrub and chaparral of the coastal mountain ranges.
C. palmeri is a large treelike shrub approaching 6 metres (20 ft) in maximum height.
Leaves have a single main vein rising from the leaf base. The thick, firm evergreen leaves are hairless, oval, and up to an inch wide, with smooth margins.
The bark is smooth and olive green, giving rise to its common name. The stem is a rough-barked trunk near the base. Branches are stiff and sharp, or spiny, at the tips. "Ceanothus" means "spiny plant" in Greek, and the species name, "spinosus", means that it is even more spiny.
The stipules (small leaf-like structures at the base of the leaf stem) are thin and fall off early.
The shrub blooms in inflorescences up to 15 centimeters long filled with clusters of white to pale blue flowers.
The fruit is a smooth, round capsule about half a centimeter wide containing three lobes. Fruits do not have horns, as do some other members of the genus.
It blooms from February to May.