J Syst Evol ›› 1981, Vol. 19 ›› Issue (3): 313-317.

• Research Articles •

### On the origin and distribution of the genus Salix in Qinghai-Xizang plateau

Fang Zhin-Fu, Zhao Shi-Dong

1.  (Institute of Forest and Pedology, Academia Sinica)
• Published:1981-08-18

Abstract: 1. Uplifting of Qinghai-Xizang plateau has brought great influence on the origination and distribution of species inside the genus Salix. There are 91 sp. (incl. 2 cult. sp.), 16 var. and 3 f. belonging to 15 Sect. in this region, among these species the endemics attain to 58 sp., 14 var. and 3 f. So it has become one of the most important centres of distribution of Salix in the world. Species common with other regions attain only to 32. Thus it is also clear that correlation between salicaceous flora in this region and that of other regions is not so much developed, and that the salicaceous flora of Qinghai-Xizang plateau was mainly originated autochthonously during the upheaval of plateau. 2. Along a demarcation line delineated from Gyirong through Lhasa and Qamdo to Lanzhou, to the north-western region the total number of species of this genus is summed up to 7 sp. and 1 var. (incl. 2 cult. sp.), and they distribute only in the West Himalaya and Pamir-Kunlun regions. Besides 2 cult. sp., there is only 1 endemic, and others all should be migrants from Europe or West Asia. In the south-eastern part, because the climate is moister, the species of Salix may be summed up to 84 sp., 15 var. and 3 f., among them 73 sp., 20 var. and 3 f. are endemics, accounting for 68 percent of the total. 3. In East Himalaya and South Henduan Shan (southward of lat. 30°N.) there are 78 sp., 12 var. and 4 f., among them 50 sp., 10 var. and 2 f. are endemics. They represent the different stages of phylogenetic development of this genus. So here may be the centre of origination and distribution of Salix species in the all Sino-Himalaya flora. The common species between East Himalaya and South Henduan Shan regions attain to 41. Because the latter forms a part of Sichuan and Yunnan plateau and the former did not become a land until Quaternary Period, the plants of the former mainly are the migrants from the latter. 4. The most characteristic group of Salix in this region is Sect. Lindleyanae Schneid. with a total of 18 sp. and 1 var. This group adapting to the somewhat environment changes is quite different from Sect. Retusae A. Kern. in the Arctic and high mountains of higher latitudes in many characters, so it should be originated autochtonously, and it is certainly not a migrant from Arctic. This Sect. seems to be developed from Sect. Floccosae Hao and in turn from Sect. Sclerophyllae Schneid. and Sect. Denticulatae Schneid. This developmental direction has assumed an important branch in the phylogenetic development of the whole genus. 5. In addition, there are two interesting and important regions on the north-eastern and eastern to Qinghai-Xizang Plateau, i. e. on the north-east Anymaqen Shan (Amnemachin mountain) and on the east Qiong Lai Shan. There are many endemic species pertaining to these two parts, among these species some may be ancient relicts since Tertiary. It is to be expected that more additional scientific results will be obtainedafter some more extensive works done in these two regions.