Arctostaphylos and Ceanothus - The Two California Shrubs Par Excellence

Ceanothus has ___ taxa, including a few outside of the California Floristic Province, even Europe?  Relatively short-lived, but very fast-growing and showy in flower.

Arctostaphylos is the crème de la crème of California shrubs, I think over 100 taxa (62 species), nearly all in the California Floristic Province and over 30 species in coast ranges alone (the center of diversity, same as with the California clovers!)

Genus is 15 million years old, but radiation/speciation began only 1.5 million years ago!  Ancestors were bifacial.

Slowish-growing, long-lived, fairly showy in flower but all on same basic plan, with no great color differences as in Ceanothus.

A genus of endemics if there is one, comparable to the proteas? And ericas of South Africa.

Regarding Arbutus:  “The divergence of North American species from Mediterranean Basin species is estimated to be between 32 and 168 million years ago.”  (Could the same ancient dates apply to the clover split also??)

Molecular systematics study (Markos et al.) showed that there are two major lineages within Arctostaphylos with multiple convegences; two beautiful examples of amazing convergent evolution are within two erstwhile “species” A. hookeri and A. uva-ursi, both of which have some infraspecific taxa in both of the two lineages!  A hookeri hookeri and A. h. hearstiorum belong together, and with A “uva-ursi” from New Jersey!, whereas three forms of A. “hookeri” from San Francisco and Marin counties belong in the other lineage, along with A. “uva-ursi” from San Mateo and Monterey counties!

Pine and Oak—the Bobsey Twins