The Floristic Characteristics and Geographical Distribution of the Rosaceae in Xizang

Abstract

Abstract:

The Rosaceae is one of the five largest families of Xizang flora, consisting of

30 genera with 242 species, the total number of species is slightly less than those of

Compositae, Graminae, Leguminosae and Ericaceae in Xizang, amounting to 62.5% of

the total number of genera and 28% of the total number of species of the rosaceous flora

in China.

The four subfamilies of Rosaceae including primitive, intermediate and advanced

groups have been found in Xizang. These groups consist of 11 types of floristic ele-

ments, i.e. 4 genera belong to cosmopolitan, 9 genera belong to North Temperate, 3, E.

Asian-N. American, 3 Sino-Himalayan, 3 Sino-Japanesa, 2 Old World Temperate, 1

Temperate Asian, 2 Mediterranean-W. and O. Asian, 1 C. Asian, I Tropical Asian and 1

endemic to China. It is obvious that Rosaceae in Xizang comprises holarctic, Ancient Me-

diterranean and paleotropical elements, among which the temperate components are the

most dominant. The characteristics of the floristic composition of Rosaceae in Xizang

may be summarized as follows:

(1) Xizang abounds in both genera and species of the family which are diverse in

forms, including the primitive, intermediate and advanced groups, (2) The geographi-

cal elements are rather complex, mostly belonging to the temperate, among which the

Sino- Himalayan components and the elements endemic to China are dominant, (3) The

proportion of plants endemic to China and distributed in Xizang is much higher than

those endemic to Xizang itself, but there exist newly arisen species and infraspecific

forms or varieties which show that the speciation is apparently still active in Xizang.

The rosaceous flora of Xizang is a combination of old and new floristic elements, based

on the old floristic components, affected by the upheaval of the Himalayas, the differen-

tiation and speciation have been taking place in the long history.

The geographical distribution of Rosaceae in Xizang may be divided into 5 regions,

i.e. the northeastern, southeastern, southern, northwestern and northern. The rosaceous

plants are most abundant in the southeastern area, next in southern area, fewer in the

northeastern and very rare in the northwestern and northern regions. The general ten-

dency of the distribution of Rosaceae in Xizang is that the number of species gradually

decreases from the southeast to the northwest and the habit gradually changes from

trees, shrubs and herbaceous plants in the southeast to cushion-like scrubs and dwarf

perennial herbs in the northwest. These facts clearly show that the uplift of the Hi-

malayas has deeply affected the phytogeographical distribution of Xizang Rosaceae.

The rosaceous flora of Xizang has close relationships with those of the adjoring

regions, i.e. Yunnan and Sichuan. Besides, it is connected with floras of Nepal, Sikkim,

Bhutan nothern Buram and nothern India, but silghtly influenced by the Ancient Medi-

terranean flora.

Key words: flora, geographical elements, geographical regionalization, Rosaceae, Xizang

Yü Te-Tsun, Lu Ling-Ti, Ku Tsue-Chih. The Floristic Characteristics and Geographical Distribution of the Rosaceae in Xizang[J]. .

[1]	LU Ling-Ti, KU Ttsue-Chih. Pleiosorbus is united with Sorbus (Rosaceae) [J]. , 2002, 40(5): 475-476.
[2]	HONG De-Yuan. Xizangia bartschioides (Hand.-Mazz.) D. Y. Hong, a new combination in Scrophulariaceae [J]. , 2001, 39(6): 544-546.
[3]	WU Peng-Cheng, JIA Yu, WANG Mei-Zhi. Phytogeographical relationships of the bryophytes between China and North America [J]. , 2001, 39(6): 526-539.
[4]	ZHU Zheng-Yin. Changruicaoia Z. Y. Zhu—A new genus of Labiatae from Mount Emei, Sichuan, China [J]. , 2001, 39(6): 540-543.
[5]	SUN Kun, ZHANG Zhi-Yun, CHEN Jia-Kuan. Floral organogenesis of Potamogeton distinctus A. Benn. (Potamogetonaceae) [J]. , 2000, 38(6): 528-531.
[6]	LU Ling-Ti. Notes on species of some genera of Rosaceae, China [J]. , 2000, 38(3): 276-281.
[7]	TAO De-Ding. The identity of the genus Xizangia Hong(Scrophulariaceae) [J]. , 1999, 37(3): 281-281.
[8]	LIANG Song-Yun. New Material of Carex Section Rhomboidales from China (2) [J]. , 1998, 36(6): 530-537.
[9]	SUN Kun, CHEN Jia-Kuan, CHEN Zhi-Duan. Progress in Studies on Floral Development of Angiosperms and Some Consideration on Future Studies [J]. , 1998, 36(6): 558-568.
[10]	Li Chao-luan. Two New Species of Ampelocissus Planch.(Vitaceae) [J]. , 1997, 35(6): 552-555.
[11]	Wang Qing-feng, Chen Jia-kuan. Floral Organogenesis of Caldesia parnassifolia (Bassi ex L.) Parl. (Alismataceae) [J]. , 1997, 35(4): 289-292.
[12]	Wang Shi-jun. A Study on Origin and Evolution of Cordaitaceae in Late Paleozoic [J]. , 1997, 35(4): 303-310.
[13]	He Chao-xing, Tao Jun-rong. A Study on the Eocene Flora in Yilan County, Heilongjiang, China [J]. , 1997, 35(3): 249-256.
[14]	Zhang Ming-li. The Geographic Distribution of the Genus Caragana in Qinghai-Xizang Plateau and Himalayas [J]. , 1997, 35(2): 136-147.
[15]	Huang Jin-ling, Ma Li-ming, Hong De-yuan. Cytotaxonomic Studies on the Genus Aspidistra II [J]. , 1997, 35(1): 14-23.

The Floristic Characteristics and Geographical Distribution of the Rosaceae in Xizang

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