''Ceanothus masonii'' is a species of

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

in the buckthorn family,

Rhamnaceae The Rhamnaceae are a large family of flowering plants, mostly trees, shrubs, and some vines, commonly called the buckthorn family. Rhamnaceae is included in the order Rosales. The family contains about 55 genera and 950 species. The Rhamnaceae h ...

, known by the common name Mason's ceanothus. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Marin County, California Marin County is a County (United States), county located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 262,231. Its county seat and ...

, where it is known only from an area near

Bolinas Bolinas is an unincorporated coastal community and census-designated place in Marin County, California, United States. As of the 2020 census it had a population of 1,483. It is located on the California coast, approximately (straight line dist ...

on the

Point Reyes National Seashore Point Reyes National Seashore is a park preserve located on the Point Reyes Peninsula in Marin County, California. As a national seashore, it is maintained by the US National Park Service as an important nature preserve. Some existing agricult ...

. It grows in the coastal

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

on the windblown bluffs..

Description

This rare shrub grows to heights approaching 2 meters. The evergreen leaves are oppositely arranged and less than 2 centimeters long. They are round to oval in shape and have tiny, sharp teeth along the edges, sometimes spine-tipped. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

is a small cluster of deep blue to purple flowers. The fruit is a capsule just a few millimeters wide, topped with minute horns. This ceanothus is closely related to '' Ceanothus gloriosus'', and may in fact be a variety of that species.California Native Plants Society Rare Plants Inventory
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References

External links

Jepson Manual Treatment of ''Ceanothus masonii''

USDA Plants Profile for ''Ceanothus masonii''

''Ceanothus masonii'' — U.C. Photo gallery
masonii Endemic flora of California Natural history of the California chaparral and woodlands Natural history of Marin County, California West Marin Plants described in 1942 Endemic flora of the San Francisco Bay Area {{Rhamnaceae-stub