Circumboreal Region


The Circumboreal Region in phytogeography is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan.
It is the largest floristic region in the world by area, comprising most of Canada, Alaska, Europe, Caucasus and Russia, as well as North Anatolia and parts of northern New England, Michigan, and Minnesota. Northern portions of the region include polar desert, taiga and tundra biomes. Many geobotanists divide Eurasian and North American areas into two distinct regions. The continents, however, share much of their boreal flora. The flora was severely impoverished during glaciations in the Pleistocene. The region is bordered by Eastern Asiatic, North American Atlantic, Rocky Mountain, Mediterranean and Irano-Turanian Regions.
There are no biological families endemic to this region, but it has endemic genera and many endemic species, especially in the mountains.

Floristic provinces

It is subdivided into a number of floristic provinces. Their delineation is debatable. According to a version of Takhtajan's classification, these are the Arctic, Atlantic European, Central European, Illyrian, Euxinian, Caucasian, Eastern European, Northern European, West Siberian, Altai-Sayan, Central Siberian, Transbaikalian, Northeastern Siberian, Okhotsk-Kamtchatkan and Canadian Provinces.