| The genus Salix Linnaeus comprises ca.350-520 species. The genus is widely distributed in temperate and boreal regions of the Northern Hemisphere, and differentiation and evolution in the Himalayan-Hengduan Mountains Center. However, there have not any comprehensive treat work for Salix in Pan-Himalayas. Some species’circumscription are unclear, and systematic positions are unresolved. The subgeneric classification of Salix is not yet clear. Hence, it is necessary to carry out a systematic work for a comprehensive taxonomic revision.In this study, more than 5440 gatherings from over 37 herbaria were examined, and 600 collections were collected from SE Gansu, SE Qinghai, W Sichuan, S Xizang and N Yunnan, and the relevant literatures were studied. The taxonomic significance of morphological characters were evaluated. The results show that number of stamens, filaments distinct or connate, bud scale margins distinct or connate, floral bract colored or colorless, ovaries stipitate or sessile, relative time of flowering and emergence of leaves, leaf blade shape and size and habit are the most reliable characters for the circumscription of sections. The bracts in female catkins deciduous or persistent, male flower with one or two glands, catkins sessile or flowering branchlet presence, the length and width of catkins, ovary hairs or glabrous, leaves indumentum type, margin dentition type are valuable in species identity in the genus.This study search out 373 names of Salix in Pan-Himalayas. One hundred and twelve and 10 varieties are recognized in Salix. Seven species and 2 varieties are numerated as dubious taxa because of the unavailability of type materials without reliable representative specimens. One new species (Salix elongata L. He & Z.X. Zhang) is descried. Four new combinations are proposed (S. coggygria var. gymnocarpa L. He, S. pella var. plocotricha L. He, S. pilosomicrophylla var. acuminatomicrophylla L. He, S. radinostachya var. weixiensis L. He). S. ludlowiana A.K. Skvortsov, S. pseudocalyculata Kimura and 5. staintoniana A.K. Skvortsov are found new in China, S. heterostemon Floderus and S. bistyla Handel-Mazzetti are new in Myanmar. Fifties species,43 varieties and 6 forms are reduced to synonymies. 5. acuminatomicrophylla K.S. Hao ex C.F. Fang & A.K. Skvortsov, S.forrestii K.S. Hao ex C.F. Fang & A.K. Skvortsov, S. gonggashanica C.F. Fang & A.K. Skvortsov, S. jichoushanica N. Chao & G.T. Gong, 5. mazzettiana N. Chao, S. neomyrtillacea Ch.Y. Yang & Z.D. Wei, S. zangica var. tibetica Z. Wang & C.F. Fang ex N. Chao are added in this work that overlooked by Flora of China. The type locality of S. gyamdaensis C.F. Fang ’Gongbo’gyamda’ is incorrect, and should be’Jomda County’, the male plants of S. dibapha C.K. Schneider, S. gonggashanica C.F. Fang & A.K. Skvortsov, S. minjiangensis N. Chao, female plants of S. pilosomicrophylla C. Wang & P.Y. Fu and S. staintoniana A.K. Skvortsov, and mature leaves of S. sikkimensis Andersson are perfected. the morphological characters of male catkins S. mazzettiana N. Chao is excluded. Morpholofical descriptions and a key to all species, distribution maps to Fig.4-102 species and 10 varieties and taxonomic notes are given.In this study, two nuclear (ETS, ITS) and three plastid (psbA-trnH, rbcL-1024R, trnC-perN1r) were employed, and 96 samples representing 50 taxa were used to reconstruct the phylogeny of Salix. The result indicates that Salix is a natural monophyletic group, the sect. Tetraspermae C.K. Schneider, sect. Pentandrae (Borrer ex Hooker) C.K. Schneider, sect. Salix and sect. Wilsonia K.S. Hao ex C.F. Fang & A.K. Skvortsov form the basal clade of Salix, and one core clade is composed three subclades. Compared with previous studies, S. sphaeronymphe Goerz is separated from sect. Salix, and S. paraplesia var. subintegra C. Wang & P.Y. Fu is separated from S. paraplesia C.K. Schneider. However, in the core clade, only Chosenia Nakai and sect. Urbanianae (Seemen) C.K. Schneider with high support values, the most group are not resolved.Based on the morphological and molecular evidence, the systematic positions of S. austrotibetica N. Chao,S. calyculata Hook. f. ex Andersson, S. camusii H. Leveille, S. cavaleriei H. Leveille, S.floccosa Burkill, S. clathrata Handel-Mazzetti,S. tengchongensis C.F. Fang, S. jingdongensis C.F. Fang, S. obscura Andersson,S. opsimantha C.K. Schneider, S. sphaeronymphe Goerz are adjusted. S. paraplesia var. subintegra C. Wang & P. Y. Fu is proposed to be a natural hybrid between S. alba L. and S. paraplesia C.K. Schneider. |
PDF Full Text Request