Phytogeographic Distribution of Carex Sect. Racemosae(Cyperaceae)

According to the history of geological events,morphological,cytological,and phytogeographical characteristics of Carex Sect.Racemosae,the origin,evolution and dispersal of this section are discussed.Carex Sect.Racemosae is thought to originate in the Eocene from South-western China where the Himalaya-Hengduan Mountains are currently located.Probable dispersal route could be postulated to start from the center northward to Central Asia,Siberia,Europa,with arrival in North America via the Greenland islands and Bering Land Bridge.After the Quaternary ice age,some flourishing species in North America may have moved back to Asia via the Bering Land Bridge,finally forming the present distribution pattern.