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 Mém. Sav. Étr. Acad. Sci. St. Pétersbourg, 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. 11.) 14 (1904). — Nakai in Jour. Coll. Sci. Tokyo, XXXI. 211 (FI. 
Kor. 11.) (1911). 
Populus Davidiana Dode in Mém. Soc. Nat. Hist. Autun, XVIII. (Extr. 
Monog. Inéd. Populus, 31, t. 11, fig. 31) (1905). 
? Populus pellostachya Dode, 1. c. t. 11, fig. 32 (1905). 
? Populus wutaica Mayr, Fremdl. Wald- u. Parkbüume, 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. Mazimowicz. Ussuri: Khabarovsk, August 23, 1903, C. S. Sargent. — 
Korea: Wanson, September 5, 1903, C. S. Sargent. 
lt is only on account of their geographical distribution that 1 refer these north- 
eastern Asiatic and Chinese forms to a distinct variety. There are living 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. 
Léveillé, Fl. Kouy-Tchéou, 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. 
