甘肃蕨类植物的地理分布及区系特点

The Phytogeographical Distribution and FloristicC haracteristics of Pteridophytes of Gansu Province

Gansu Province is rich in Pteridophytes.Up to now,there are 34families,78 genera representing 292 epecies,6 varieties recognized.According to phytogeographical and climatical characteristics of Gansu aswell as species and disrributive conditions,PteridoPhytes in Gansu maybe diveded into 4 phyttogeographical distribution regions:the Pteridop-bytes region of Hexi Corridor,Pteridophytes region of the Loess plateau,Pteridophytes region of Lungnan mountains,Pteridophytes region of highmountains with cold climate of Gannan and Qilianshan.The geographical compositions of Pteridophvtes flora of Gansu arefundamentally simiar to those of Southwest China,East China and Japan,And all of tham are constituted with the Dryopteridaceae,Athyriaceaeand Polypodiaceae as the main parts of floristiceomposition.Furthermore,Polystichum,Dryopteris and Athyrium are Their cardnal representatives,and there are also more tropical and subtropical genara.