Rocky Mountain region

The Rocky Mountain Floristic Region, also known as the Rocky Mountain Floristic Province, is a floristic region within the Holarctic Kingdom in western North America (Canada and the United States) delineated by Armen Takhtajan and Robert F. Thorne. The region extends from Kodiak Island in Alaska to the San Francisco Bay Area and Sierra Nevada in California. The Vancouverian Province comprises the coastal part of the region for its entire length, including the Pacific Coast Ranges, and the Rocky Mountain Province includes the Rocky Mountains and associated ranges. There are no endemic plant families in the region but many endemic genera and species.

It spans from Kodiak Island of Alaska approximately to the San Francisco Bay Area and Sierra Nevada of California, running between the shore of the Pacific Ocean on the west and the Great Plains on the east, along the Rocky Mountains and Pacific Coast Ranges. It is bordered by the Canadian Province of the Circumboreal Region in the north, by the North American Prairies Province of the North American Atlantic Region in the east and by the Californian Province of the Madrean Region in the south. The borders with the Canadian and Californian Provinces are vague.

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