吉首市维管植物科的区系性质

吉首市地处云贵高原东缘, 境内有维管植物186 科, 662 属, 1 534 种. 从科的等级水平对其区系分析表明, 这些维管植物中有蕨类植物 29科, 区系成分为世界分布 9 科、 热带分布 8 科、 热带至亚热带分布 11科、 温带分布 1 科, 以热带至亚热带分布比重最大,占 37. 93%; 裸子植物 5科, 除 1科为世界分布外,其余 4 科都是亚热带区系的代表;被子植物 152 科,其中世界分布 33科、 热带分布 8科、 热带至亚热带分布 40 科、 热带至温带分布 38 科、 亚热带至温带分布 10科、 温带分布 16科、 亚洲特有科 7 科,以热带至亚热带、 热带至温带比重较大, 两者合计占 51. 32%. 从被子植物的优势科和表征科分析, 38个优势科中除了 13个为世界分布外,另外 25 个也是以热带至亚热带( 9 科)和热带至温带( 11科) 比重较大,两者合计占 52.64%;表征科 14 科,热带至亚热带( 4科) 、 热带至温带( 7科) 占主导, 二者合计占 78. 57%. 以上结果表明该地区维管束植物具有明显的亚热带性质,为热带向温带区系过渡的类型.

Analysis at Family Level of Geographical Elements of Vascular Plants Flora in Jishou County, Hunan China

Jishou county locates at the east of Yungui plateau with rich plants resources. There are 1 534 species under 662 genera belonging to 186 families of vascular plants in this area. The flora analysis at family level shows that: (1)There are 29 families of pteridophyta: 9 cosmopolitan,8 tropic,11 trop. to subtrop.,and 1 of temperate zone respectively, and the trop. to subtrop. type has the most ratio (38%). There are 5 families of gymnosperm, 4 are representative types of subtrop. and the other cosmopolitan. Of the 152 families of angiosperm,33 are cosmopolitan families,8 tropic,40 trop. to subtrop.,38 trop. to temp.,10 subtrop. to temp.,16 temperate,and 7 endemic families of Asia. The total of trop. to subtrop. and trop. to temp. has the most ratio (51.32%). According to the analysis on the dominate and representative family of angiosperm, among the 38 dominate families, except 13 types of cosmopolitan, the total of the types of trop. to subtrop. (9) and trop. to temp.(11) also has the most ratio (52.64%). Among the 14 representative families, the total of the types of trop. to subtrop.(4) and trop. to temp.(7) has the most ratio (78.57%). This paper indicates that Jishou county belongs to the transitional area between tropical and temperate with obvious characters of subtropical flora.