Included here is a biozone extending from the Gulf of Alaska to California covering some 25 degrees of latitude but is never more than about 350 km wide. Kodiak Island in Alaska forms its northern limit and from there it continues eastward and southward as a narrow strip near the coast through British Columbia including Vancouver Island and Haida Gwaii (Queen Charlotte Islands). In Washingtom and Oregon it broadens out to include the Cascade Mountains as well as the Coastal Range and Olympic Mountains. It then follows the Coastal Range through California nearly as far as San Francisco and then departs slightly from the coast and extends to the southern tip of the Sierra Nevada.
Of the endemic and near endemic vascular plants so far recorded there are about 491 species, subspecies and varieties in 192 genera and 50 families. There are about 23 endemic or near endemic genera (marked red) but no endemic families. However, species of the family Sarraceniaceae are confined to North and South America.
This list has been compiled with the help of Ed Alverson (Oregon).
Buckingham, N. 1996. Flora of the Olympic Peninsula. Pacific Northwest Naturalist.
Douglas, G. W. 1996. Endemic vascular plants of British Columbia and immediately adjacent regions. The Canadian Field-Naturalist, 110: 387-391.
Kruckeberg, A. R. 1969. Plant life on serpentinite and other ferromagnesian rocks in northwestern North America. Syesis, 2: 15-114.
Ogilvie, R. T. 1994. Rare and Endemic Vascular Plants of Gwaii Haanas (South Moresby) Park, Queen Charlotte Islands, British Columbia. Forest Resource Development Agreement (FRDA) Report No. 214.
Qian, H. 1999. Floristic analysis of vascular plant genera of North America north of Mexico: characterization and phytogeography. Journal of Biogeography, 26: 1307-1321.
Reagon, A. B. 1934. The flora of the Olympic Peninsula, Washington. Iowa Academy of Science.
Schofield, W. B. 1969. Phytogeography of northwestern North America: bryophytes and vascular plants. Madroño, 20: 155-207.
Shevock, J. R. 1996. Status of rare and endemic plants. U. S. Forest Service, Pacific Southwest Region, San Francisco, California.
Smith, J. P. & Sawyer, J. O. Endemic vascular plants of northwestern California and southwestern Oregon. Madroño, 35: 54-69.
Taylor, J. A. & Calder, M. G. 1968. Flora of the Queen Charlotte Islands. Part I: Systematics of the Vascular Plants. Part 2: Cytological Aspects of the Vascular Plants. Canada Department of Agriculture.