Plant diversity in California

Thrips are dependent on plants, most species either feeding on the living tissues of leaves or flowers, but with a large proportion of species feeding on fungal spores or fungal hyphae on dead branches and leaves. It might therefore be thought that thrips faunal diversity and the available floral diversity will be correlated, but this seems not to be so. Across the world, thrips diversity is generally correlated more with decreasing latitude, presumably with rising temperature and humidity, than with increasing floral diversity.

The plant life of California is diverse and unique, as indicated by the following statements derived from information in the essential floristic resource: Raven PH & Axelrod DL (1978). Origin and relationships of the California flora. University of California Publications in Botany 72: 1–134.

1. There are more than 5000 native vascular plants recorded from California.
2. There are 4500 vascular plant species in the California Floristic Province, the area between the Sierra and the coast from southern Oregon to northern Baja California.
3. This total of 4500 is more than the entire central and northeastern United States and adjacent Canada, an area some 10 times larger.
4. Within the California Floristic Province, almost 50% of the 4500 species are endemics.
5. Almost 30% of Californian plant species are annuals. See: Calflora