J Syst Evol ›› 1995, Vol. 33 ›› Issue (2): 144-160.

• Research Articles • Previous Articles     Next Articles

A Study on the Geographic Distribution of the Genus Kobresia Willd.

Zhang Shu‐ren, Liang Song‐yun, Dai Lun‐kai   

  • Published:1995-03-10

Abstract: The genus Kobresia Willd. , including four sections with 64 species and 5 varieties, belongs to the tribe Cariceae in the family Cyperaceae. The tribe is the most advanced group in Cyperaceae, while the genus is primitive in the tribe. Kobresia is distributed in the temperate to frigid zones of the Northern Hemisphere. All species and varieties, except K. macrocarpa, are found in Asia. They are mainly distributed in the Himalayas and Hengduan Mountains. The genus is especially adapted to frigid habitats, and exists in alpine environments and high latitudes. According to the floristic regionization of Takhtajan (1986), Kobresia is distributed in four regions of the Holarctic Kingdom and one region of the Paleotropical Kingdom. (1) The Circumboreal Region: six species, 8.70% of the total taxa of Kobresia. These species have wide distributions, and two of them, K. bellardii and K. caricina, can be seen almost in the whole range of the genus. (2) The Eastern Asiatic Region: fifty-one taxa, 73.91% of the total taxa, and twenty-two endemic species. This region is divided into the Sino-Himalayan Forest Subkingdom and Sino-Japanese Forest Subkingdom by Wu (1979). Forty-one taxa occur in the former, and twelve of them are endemic. Only eight taxa occur in the latter. (3) The Rocky Mountain Region: three species, 4. 35% of the total taxa, and one endemic species. (4) Irano-Turanian Region: thirty-ninespecies, 56.52% of the total taxa of Kobresia, and six endemic species. According to the scheme of the Chinese floristic division established by Wu, thirty-six taxa exist in the Qinghai-Xizang Plateau Subkingdom, with five endemic. (5) Malesian Region: one species, Kobresia kobresioidea (Kükenth.) Kern, which is primitive in the genus and endemic to the northern mountains in Summatra. In Asia, more than 90% of the total taxa of Kobresia, are found in the Himalayas and Hengduan Mountains. These taxa include the most primitive to the most advanced ones in the genus. The area is not only the center of density, but also the center of diversity of Kobresia, thus it is the center of the distribution of the genus. Kobresia is closely related to the genus Schoenoxiphium, which is confined to Madagascar and southeastern Africa. They might have had a common ancestor in the Gondwanaland. With drifting of the India Plate, the ancestor of Kobresia was brought to Eurasia, and differentiated in the Himalayas and Hengduan Mountains where India met Eurasia. The Indian land mass connected Asia in the early Tertiary, and Kobresia probably began to originate in the same time in the Himalayas. The genus reached its greatest speciation with the lifting of the Himalayas, and dispersed along the mountains in the Northern Hemisphere to Europe and Siberia. From Europe, it arrived at Greenland and eastern Canada. From Siberia, it reached Alaska through the Bering strait, and came down along the Rocky Mountains to Colorado.

Key words: Kobresia, geographical distribution, origin, dispersal