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The Eastern Asiatic Region (also known as Oriasiaticum, Sino-Japanese Region, East Asian Region, Temperate Eastern Region) is the richest floristic region within the Holarctic Kingdom and situated in temperate East Asia. It has been recognized as a natural floristic area since 1872 August Grisebach's volume Die Vegetation der Erde and later delineated by such geobotanists as Ludwig Diels, Adolf Engler (as Temperate Eastern region), Ronald Good (as Sino-Japanese Region) and Armen Takhtajan.
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The Eastern Asiatic Region is dominated by very old lineages of gymnosperms and woody plant families and is thought to be the cradle of the Holarctic flora. Moreover, this floristic region wasn't significantly glaciated in the Pleistocene, and many relict Tertiary genera (such as Metasequoia glyptostroboides, ancestors of which were once common throughout the Northern Hemisphere up to subpolar latitudes) found refuge here.
Endemic flora
The Eastern Asiatic Region endemic flora is characterized by:
Endemic families
Endemic genera
Approximately eight other families are shared with tropical Southeast Asia (Nageiaceae, Rhodoleiaceae, Daphniphyllaceae, Pentaphyllaceae, Duabangaceae, Mastixiaceae, Pentaphragmataceae, Lowiaceae). As has long been noted, many relict genera occurring in East Asia, such as Liriodendron and Hamamelis, are shared with temperate North America, especially the North American Atlantic Region.
Adjacent Regions
The Eastern Asiatic Region is bordered by the Circumboreal Region of the Holarctic Kingdom in the north, the Irano-Turanian Region of the same kingdom in the west and Indian, Indochinese and Malesian Regions of the Paleotropical Kingdom in the south. It comprises the southern part of the Russian Far East, southern part of Sakhalin, Manchuria, Korea, Japan, Taiwan, relatively humid eastern part of the mainland China from Manchuria and the seashore to Eastern Himalaya and Kali Gandaki Valley in Nepal, including Sikkim, northern Burma and northernmost Vietnam (parts of Tonkin).
Subdivisions
According to a version of Takhtajan's classification, the Eastern Asiatic Region is further subdivided into 13 provinces; however, the number and delimitation of the southern provinces is disputed and varies even across Takhtajan's work.