The California Floristic Province
Being a California native myself I have a fascination with California’s native flora. There are about 6300 native taxa of plants found in California, and a third are found nowhere else but the limited area that comprises the California floristic province. It has the highest diversity of plant species in North America, north of tropical Mexico.
The plants of California are specially adapted for the Mediterranean climate here. Mediterranean climates have long, dry summers and cool, moist winters. In Mediterranean climates the majority of the precipitation occurs during the moist winter months, and summer months receive almost no rainfall, which often means 6-8 months of no rains. For this reason many plants here have switched around the normal seasonal growing patterns. Spring is triggered by the autumn rains, and during the dry summer months plants enter their dormancy.
Mediterranean climate zones comprise only 3% of the Earth’s landmass, but account for 10% of the known plant species. In addition to California, Mediterranean climates are found in only four other areas of the world: the Mediterranean Basin, the Cape region of South Africa, central Chile, and southwestern Australia. Many of the plants used in ornamental gardens and propagated by the nursery industry have ancestral orgins in the Mediterranean climes of the world. This climate has truly created an amazing diversity of flora.
(California Floristic Province Map and statistics from California Native Plants for the Garden, Bornstein, Fross, & O’Brien, Cochuma Press, 2005.)
(Mediterranean Climate Map via wikipedia.)