Studies on the Distribution Patterns of Some Significant Genera in Orchid Flora

Abstract

Abstract:

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 babitat 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 ZayÜ), 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 Re-

gion, 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), ZayÜ) 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. Stig-

matosa, 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 distribu-

tion.

II. Neofinetia, Vexillabium and Sedirea all belong to typical groups of distribution in

the Sino-Japanese Subregion. Their distribution patterns are as follows:

1. Neofinetia (only one species) is distributed in Japan: Honshu (west of Kanto),

Shikoku, Kyushu (Tanega-shima, Yaku-shima), Ryukyu-qunto (Amamio-shima, Oki-

Nawa-jima) and Daito-shoto; S. Korea (Cheju-do) and China and grows at 400--1300 (--

1520) m alt. In China its distribution ranges from Fujian (Chongan), Zhejiang (Putuo,

Shengsi and Songyang), Jiangxi Lushan Mountain, Yushan and Yichun, Hubei (Lichuan

and Hefeng) to Sichuan (Wan Xian, Pingchang, Tongjiang, Guangyuan, Qingchuan (alt.

1520 m), Beichuan, Emei Mountain) and Gansu (Wen Xian). The Emei Mountain is its

western limit (Fig. 5).

2. Vexillabium (only four species) is distributed in Japan: Honshu (Izu-hanto,

Mieken), Shikoku (Yaku-shima); S. Korea (Cheju-do) ; N. Philippines (Batan Is. ) and

China at 450-1300 (-1600) m alt. In China its distribution ranges from Taiwan

(Taidong, Lan Yu), through Zhejiang (Lin’an, Tianmu Mountain and Suichuan), Hunan

(Xinning), Shaanxi (Yang Xian) to Sichuan (Nan-chuan, Jinfo Mountain and Beichuan

(alt. 1600 m)). The Minjiang River is its western limit (Fig. 6).

3. Sedirea (only two species) is distributed in Japan: Honshu, Shikoku, Kyushu

(Tanega-shima, Yaku-shima and Nakano-shima) and Ryukyu-qunto (Amamio-shima and

Okinawa-jima); S. Korea (Cheju-do) and China at 300--1300 (--1400) m alt. In China its

distribution ranges from Fujian (Chong´an, Wuyi Mountain), Zhejiang (Wencheng, Tain-

tai Mountain, Longquan, Lin'an, Xinchang and Kaihua), Hunan (Sangzhi, Shuangpai,

Shaoyang and Tongdao), Hubei (Xianfeng), Sichuan (Chengkou and Leibo (alt. 1400

m)), Guizhou (Jiangkou and Songtao) and Yunnan (Yingjiang alt. 1350 m). The Leibo is

its western limit (Fig. 7).

The vertical distribution of Neofinetia, Vexillabium and Sedirea is lower in general, but

little higher in western marginal regions of their distribution.

Above distribution patterns can be summarized as follows: (1)Risleya, Diplomeris,Di-

phylax and Platanthera subgen. Stigmatosa belong to typical groups of the Sino-Himalayan

Subregion distribution, among them Risleya, Diphylax and Platanthera subgen. Stigmatosa

all have Mt. Emei as their eastern limit in Sichuan, while Diplomeris has somewhat over the

Mountain as its eastern limit of distribution in Sichuan; (2) Neofinetia, Vexillabium and

Sedirea belong to typical genera of the Sino-Japanese Subregion distribution, among them

Vexillabium has Beichuan of eastern Minjian River, Neofinetia has Mt. Emei and Sedirea

has Leibo as their western limit in Sichuan. Based on the distribution patterns of above six

genera and one subgenera, the boundary between the Sino-Himalayan Subregion and the

Sino-Japanese Subregion of the flora in Sichuan is exactly in between the Mt. Emei and the

Minjiang River. Therefore, we may say that the boundary is identical to the one between the

Kham-Dian Old Land (Palaeo-Hengduan Mountains) and the Yangtze Plate in the Early

Tertiary. The isolated characteristics of the distribution patterns of seven groups in orchids

is related to topography, altitude, climate and the geological history.

The concrete boundary between the Sino-Himalayan Subregion and the Sino-Japanese

Subregion of the flora in Sichuan may be made from Nanping (Jiuzaigou), Songpan

(Huang-longshi), Maowen, Wenchuan, Guan Xian (Mt. Guangguang), Baoxing, Mt. Er-

lang, Mt. Emei, Shimian, Mianning, Xichang, Dechang, Miyi up to Panzhihua city. The

above study on the distribution patterns of the seven groups in orchids has definite signifi-

cance for the definition on the boundary between Sino-Himalayan Subregion and the Sino-

Japanese Subregion in Sichuan.

Key words: Orchies, Distribution patterns, Floristic regionalization, Sino-Japanese subregion, Sino-Himalayan subregion

Lang Kai-yong. Studies on the Distribution Patterns of Some Significant Genera in Orchid Flora[J]. .

Studies on the Distribution Patterns of Some Significant Genera in Orchid Flora

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