西北干旱荒漠区种子植物科的区系分析

Floristic analysis of seed plant families in West-North Desert of China

西北干旱荒漠区分布有种子植物 82科、484属、1 70 4种 ,优势现象明显 ,优势科 1 1个 ,它们是菊科、豆科、禾本科、藜科、十字花科、蓼科、莎草科、毛茛科、蔷薇科、唇形科和百合科 ;表征科 8个 ,它们是香蒲科、麻黄科、柽柳科、蒺藜科、胡颓子科、藜科、眼子菜科和蓼科。地理成分多样 ,其中以世界广布成分为主 ,共 3 7科 ,占总科数的 45 .1 2 % ,其次为温带成分 (包括热带至温带、亚热带至温带、温带、温带至寒带 ) ,共有 3 1科 ,占总科数的 3 7.80 % ,热带成分、热带至亚热带成分较少 ,共 1 4科 ,占总科数的 1 7.0 7%。

There are 82 families 484 genius 1704 species seed plants and obvious dominant phenomenon in West North Desert of China.There are 11 dominant families (Compositae?Leguminosae?Graminaea?Chenopodiacea?Cruciferae?Polygonaceae?Cyperaceae?Ranunculaceae?Rosaceae?Labiatae?Liliaceae) and 8 typical families (Typhaceae?Ephedraceae?Tamaricaceae?Zygophyllaceae?Chenopodiaceae?Elaeagnaceae?Polygonaceae?Potamogetonaceae).The flora has a diverse geographical elements,the overwhelming number is cosmopolitan elements (37 families) accounting for 45.12%,the second number is temperate elements (31 families) accounting for 37.80%,including tropical to temperate,subtropical to temperate,temperate,temperate to frigid.Pure tropical and tropical to subtropical families is only 14 families accounting for 17.07%.This phenomenon is the result of the broad latitudes and diversifies habitats in West North of China.It is shown that most of the dominant families are cosmopolitan,most of typical families are temperate.