Ceanothus maritimus is a rare, narrow endemic species of shrub in the Buckthorn family (Rhamnaceae) known by the common name Maritime Ceanothus. It is endemic to San Luis Obispo County, California, where it is known from only a few occurrences in the vicinity of Hearst Ranch. It shares the same range as the similarly rare Ceanothus hearstiorum, growing on the coastal bluffs.
This species looks unlike other Ceanothus and is said to resemble the non-native Cotoneaster. This is a spreading or ascending shrub under a meter in height with reddish gray bark aging to gray. The firm evergreen leaves are oppositely arranged, each oval or oblong in shape with a pointed, flat, or notched tip. Its short leaves are shiny green on top and woolly underneath, with their edges curled under and sometimes toothed.
The flower cluster is a small cluster of deep blue to off-white flowers. The fruit is a capsule, generally rounded with tiny horns on top. This is an attractive, adaptable, long-lived plant that is great for central coastal gardens.