雅鲁藏布江大拐弯地区蕨类植物科属区系特征分析

雅鲁藏布江大拐弯地区蕨类植物区系共含４５科、１０８属。主要科为鳞毛蕨科Ｄｒｙｏｐｔｅｒｉｄａｃｅａｅ（８０／５，种数／属数）、水龙骨科Ｐｏｌｙｐｏｄｉａｃｅａｅ（６５／１４）、蹄盖蕨科Ａｔｈｙｒｉａｃｅａｅ（４５／１１）、铁角蕨科Ａｓｐｌｅｎｉａｃｅａｅ（２３／３）、中国蕨科Ｓｉｎｏｐｔｅｒｉｄａｃｅａｅ（１９／６）、金星蕨科Ｔｈｅｌｙｐｔｅｒｉｄａｃｅａｅ（１８／９）、凤尾蕨科Ｐｔｅｒｉｄａｃｅａｅ（１３／２）、卷柏科Ｓｅｌａｇｉｎｅｌａｃｅａｅ（１２／１）和膜蕨科Ｈｙｍｅｎｏｐｈｙｌａｃｅａｅ（１１／３）。主要属是耳蕨属Ｐｏｌｙｓｔｉｃｈｕｍ，鳞毛蕨属Ｄｒｙｏｐｔｅｒｉｓ，铁角蕨属Ａｓｐｌｅｎｉｕｍ，蹄盖蕨属Ａｔｈｙｒｉｕｍ等系统发育上较高级的类群；无典型的特有属，可认为它是随青藏高原隆起而形成的较年轻的蕨类区系。其热带成分科属虽多（科占６２２％，属占６７６％），但优势科、优势属均为广布类型。本区蕨类植物的起源是古老的热带亚洲成分。

Analyses of the Floristic Features on the Families, Genera of Pteridophyta from the Big Bend Region at Yalu Tsangpo (River), Xizang (Tibet), China

The pteridophytic flora from the Big Bend at Yalu Tsangpo (River) comprises 108 genara, 45 families. The representative families are Dryopteridaceae (80/5, No. of sp. /No. of gen.), Polypodiaceae (65/14), Athyriaceae (45/11), Aspleniaceae (23/3), Sinopteridaceae (19/6), Thelypteridaceae (18/9), Pteridaceae (13/2), Selaginellaceae (12/1) and Hymenophyllaceae (11/3). The main genera are Polystichum, Dryopteris, Asplenium, Athyrium, and some genera in Polypodiaceae, which are some phylogenically higher taxa; and in this flora, there are no typical gernera which are endemic to this region. It can be said that the pteriophytic flora of Yalu Tsangpo (River) Big Bend is a younger area one which developed with the heaving of the Qingzang Plateau. It is rich that the families (62.2% to total) and genera (67 6% to total) are tropical taxa, but the top families and genera are cosmopolitan taxa. This pteriophytic flora developed from an ancient one of tropical Asia.