The genus Ceanothus is represented by over 30 species in California alone. Squaw carpet, C. prostratus, the topic of my last post is a prostrate, ground-hugging shrub with lavender or purple flowers that blankets dry slopes, usually near ponderosa pine forests. In contrast, whitethorn (Ceanothus cordulatus) is another member of the same genus that has white (or ivory) flowers and grows as a flat-topped spreading shrub that can reach heights of six feet and a diameter of ten to twelve feet or more. It is sometimes difficult to remember that these two visually different plants belong to the same genus. Ceanothus plants readily hybridize and thus identification if often confusing.
Whitethorn is a native perennial found in California, Nevada and Oregon. Like all ceanothus, whitethorn has five petals and five sepals. The flowers are dense clusters and have a strong fragrance. Whether this scent is disagreeable or pleasant is debatable. The evergreen leaves alternate on the many intricately branched stems that end in sharp spines. The common name whitethorn derives from both the spines and the silvery or whiteish color of the branches. The seeds are contained in small capsules.
Whitethorn is a source of food and shelter for wildlife. Insects pollinate the flowers in return for the sweet nectar. Deer browse this shrub, although it is considered poor feed for domestic livestock. Birds, rodents and small animals find shelter amid the tangle of branches and eat the seeds. Whitethorn is also the host for several species of butterfly larvae.
The leaves and flowers can be brewed into, in my opinion, a barely passable tea.
Forest fires activate germination of whitethorn seeds. I am not certain how this is determined, but whitethorn seeds are reputed to remain dormant for over 200 years. In any case, the seeds are long-lived.
C. cordulatus is also called mountain whitethorn or simply ceanothus. The name snowbush is often associated with whitethorn. And indeed, a whitethorn in full blossom often does resemble a snow-covered bush. Snowbush, however, is usually considered the common name of a different Ceanothus species. Between hybridization and visual similarities among Ceanothus species, this is a confusing genus.
These whitethorn plants were photographed near Crystal Lake in Shasta County CA.