兰科植物区系中一些有意义属的地理分布格局的研究

STUDIES ON THE DISTRIBUTION PATTERNS OF SOME SIGNIFICANT GENERA IN ORCHID FLORA

本文从兰科植物中一些属于中国-喜马拉雅植物亚区和中国-日本植物亚区典型分布属(或亚属)的地理分布格局的研究,提出此两个植物亚区在我国四川省境内是以峨眉山和岷江为其分界,及这条线的走向是从南坪(九寨沟)、松潘(黄龙寺)、茂汶、灌县(光光山)、宝兴、二郎山(天全以西)、峨眉山、石棉、西昌、德昌、米易至攀枝花市。

The orchids represent one of the largest families of flowering plants in the world, Their flower structure is evolutionarily highly specialized and systematically, they are the most advanced groups in plant kingdom of the world. The habitat of orchids is more special than other families in flowering plants. Their distribution has higher regularity and possesses important significance for studying floristic character and region alization. The present paper proposes a concrete boundary between the Sino-Himalayan Subregion and the Sino-Japanese Subregion in Sichuan Province, based on the distribution patterns of some orchid genera typical of the two subregions. I. Risleya, Diplomeris, Diphylax and Platanthera subgen. Stigmatosa all belong to the typical groups of distribution in the Sino-Himalayan Subregion. Their distribution patterns are as follows; 1. Risleya (only one species) is distributed in Sikkim, N. Burma and S. W. China and grows at (1041-) 2900-4200 m alt. In China its distribution ranges from Xizang (Tibet) (Mainling and Bomi), Yunnan (Weixi) to Sichuan (Gongga Mountain and Emei Mountain (alt. 1041 m)). The Emei Mountain is its eastern limit (Fig. 1). 2. Diplomeris (only two species) is distributed in M. Nepal to Bhutan (alt. 500-1000 m) , N. E. India, Burma, the northest Vietnam (Sa-Pa alt. 1000 m) and China and grows at (500-) 1500-2600 m alt. In China its distribution ranges from Xizang (Tibet) (Medog alt. 1000 m) , Yunnan (Gongshan) , Sichuan (Kangding, Hejiang and Xuyong) , Guizhou (Xingyi) to Guangxi (Mashan). Hejiang in Sichuan is its eastern limit (Fig. 1) 3. Diphylax (only three species) is found in M. Nepal, Sikkim, N. Burma and S. W. China at (1750-) 2500-4200 m alt. In China its distribution ranges from Xizang (Yadong, Qonggyai, Medog and Zayu), Yunnan (Gongshan, Deqen and Yiliang alt. 1750 m), Sichuan (Emei Mountain alt. 1900 m) to Guizhou (Fanjing Mountain alt. 1800 m). The Emei Mountain is its eastern limit (Fig. 2). 4. Platanthera subgen. Stigmatosa (including 12 species) is found from Kashmir Region, Pakistan (Hazara), through Nepal, Sikkim, Bhutan, N. India (Kumaon, Darjeeling, Simla) , N. Burma to S. W. China at (1500-) 2300-4500 m alt. In China its distribution ranges from Xizang (Gyirong, Zhangmo, Rongxar, Dinggye, Yadong, Cora, Mainling, Bomi, Medog (alt. 1500 m), Zayu) through Yunnan (Gongshan, Deqen, Weixi, Fugong, Bijiang, Lijiang, Dali, Heqing, Luquan, Kunming and Jingdong), Sichuan (Muli, Miyi, Huili, Huidong, Puge, Xichang, Xide, Maianning, Yuexi, Meigu, Erlang Mountain, E-bian, Emei Mountain, Honya and Guan Xian) to Guizhou (Zhenfeng). The Emei Mountain is its eastern limit (Fig. 3-4). According to the structure of gynostemum and form of labellum of the subgenus. Stigmatosa, their species belong to Platanthera unquestionably, although they are different from the other members of Platanthera due to their inconvex stigma (not concave) and sepals with mammillary-ciliate. The stigma of this group exhibits a series of evolutionary trends; from stigma single, convexly elliptic and located near the rear of spur mouth (in P. stenantha) ; to stigma single, shape of a saddle, and located near the front of spur mouth (in P. bakeriana); and to stigma double, separately located at front of spur mouth (in other ten species). The Platanthera subgen. Stigmatosa is confined to the area from the south fringe of Xizang Plateau (from Kashmir Region to N. E. India) through N. Burma to the Hengdu-an Mountain Region in China. It seems that the subgenus. Stigmatosa has been affected by upheaval of this area, which caused a series of variation and differentiation uninterruptedly, giving rise to this group due to the long-term selection. The vertical distribution of Risleya, Diplomeris, Diphylax and Platanthera subgen. Stigmatiosa is higher in general, but little lower in some marginal regions of their distribution. I . Neofinetia, Vexillabium and Sedirea all belong to typical groups of distribution in the Sino-Japanese Subregion. Their distribution patterns are as follows: 1. Neofinetia (o