24 WILSON EXPEDITION TO CHINA 



country and woods from river-level up to 1500 m. altitude. It is a rather slender 

 shapely tree, 20-25 m. or more tall, with a straight trunk clear of branches for 

 10-15 m. and clothed with smooth pale gray bark which on old trees and near 

 the ground becomes dark and slightly fissured. The branches are thin, ascending- 

 spreading and form an oval crown. The leaves vary considerably in degree of 

 pubescence, but on old trees they are glabrous at maturity. On young trees and 

 on adventitious shoots they are densely pubescent. 



Pictures of this tree will be found under Nos. 523, 531, 540, 543, 564 and 0181 of 

 the collection of my photographs and also in my Vegetation of Western China, Nos. 

 397, 398, 399 and 400. E. H. W. 



Populus tremula Linnaeus, var. Davidiana Schneider, var. nov. 



Populus tremula Maximowicz in Mem. Sav. Str. Acad. Sci. St. Petersbourg, IX. 



245 (Prim. Fl. Amur.) (1859). — Burkill in Jour. Linn. Soc. XXVI. 557 (pro 



parte maxima) (1899). — Komarov in Act. Hort. Petrop. XXII. 14 (Fl. 



Mansh. II.) 14 (1904). — Nakai in Jour. Coll. Sci. Tokyo, XXXI. 211 {Fl. 



Kor. II.) (1911). 

 Populus Davidiana Dode in Mem. Soc. Nat. Hist. Autun, XVIII. {Extr. 



Monog. Ined. Populus, 31, t. 11, fig. 31) (1905). 

 f Populus pellostachya Dode, 1. c. t. 11, fig. 32 (1905). 

 f Populus wutaica Mayr, Fremdl. Wald- u. Parkbaume, 494 (1906). 



Western Hupeh: Hsing-shan Hsien, upland thickets, alt. 1600- 

 2500 m., October 1907 (No. 722, in part; tree 8-24 m. tall); same 

 locality (Plant No. 1459; young plants in the Arnold Arboretum); 

 Fang Hsien, alt. 1600-2000 m., October 15, 1907 (No. 722, in part; 

 tree 8-24 m. tall, girth 0.5-1.5 m.); mountains north of Ichang, May 

 1901 (Veitch Exped. No. 1886; tree 8 m. tall; female flowers). 

 Western Szech'uan: west of Kuan Hsien, Pan-lan-shan, woodlands, 

 alt. 3000 m., October 1910 (No. 4347) ; north of Tachien-lu, woodlands, 

 alt. 2500 m., October 1910 (No. 4358; tree 6-16 m. tall, bark gray, 

 smooth). Chili: Jehol, A. David (No. 1687, type of the variety); 

 Weichang, 1910, W. Purdom (No. 11); Hsiao-Wu-tai-shan, alt. 2000 

 m., Aug. 5, 1913, F. N. Meyer (Nos. 43, 1113). 



NORTHEASTERN ASIA. Mandshuria: Mukden, May 29, 1906, F.N. 

 Meyer (No. 101). Amur: "ad fl. Amur," 1855, R. Maack (Nos. 10, 11); 

 Amur, C. Maximowicz. Ussuri: Khabarovsk, August 23, 1903, C. S. Sargent. 

 Korea: Wanson, September 5, 1903, C. S. Sargent. 



It is only on account of their geographical distribution that I refer these north- 

 eastern Asiatic and Chinese forms to a distinct variety. There are hving plants of 

 some of Wilson's numbers in the Arnold Arboretum. It is possible that these plants 

 when fully grown may present some characters to distinguish the eastern forms from 

 those of the Altai and Europe. Even to separate var. Davidiana from the following 

 species is a difficult task. 



Leveill6, Fl. Kouy-Tcheou, 380 (1915), mentions Bodinier's No. 2101 from Kouy- 

 yang, February 1898, as P. tremula. 1 have not seen this specimen, which may 

 belong to our variety. 



