4G0 WILSON EXPEDITION TO CHINA 



m 



Betula Wilsonii Bean in Kew Bull. Misc. Inform. 1914, 30 (1914); Trees <St 

 Shrubs BHt. Isl I. 264 (1914). 



Western Szech'uan: Wa-shan (not Wushan), alt. 2100-2800 

 m., June and October 1908 (No. 1140, type of B. Wilsonii; shrub 

 1.5-3 m. tall, hanging down over cliffs; flowers and old fruits); 

 same place, alt. 2800 m., July 1902 (Veitch Exped. No. 4490; shrub 

 2.4 m. tall; young fruits) ; Mupin, alt. 2300 m., October 1910 (No. 4299; 

 prostrate and hanging from cliffs; fruits); southeast of Sungpan Ting, 

 valley of Lungan River, 2800 m., August 1910 (No. 4299^ prostrate 

 over cliffs; fruits); west of Kuan Hsien, Pan-lan-shan, alt. 2000- 

 2800 m., October 1910 (No. 4299^; prostrate and hanging down over 

 cliffs; fruits); ''ad flum. Honton, infra pagum San shei," August 13, 

 1885, G. N. Potanin (type, ex Batalin). 



The original description of this species has been overlooked by Bean, and 

 Winkler does not mention it. It is one of the best marked Birches with its very short 

 petioles and its many nerved leaves which, like the branehlets, are covered beneath 

 with a somewhat brownish silky pubescence. It is very nearly related to B. Dela- 

 vayi Franchet, from which it differs in the characters given in the key. 



On the moist rocks and cliffs of the forest-covered higher mountains of western 

 Szech'uan this interesting Birch is common. Usually all its slender whiphke 

 branches hang down over cliffs and boulders, but often it is a shrub from 1 to 3 m. 

 high with decumbent and prostrate branches. E. H. W. 



Betula Delavayi Franchet in Jour, de BoL XIII. 205 (1899).— 

 Burkill in Jour. Linn, Soc. XXVI. 498 (1899). — Winkler in Engler, 

 Pflanzenr. IV.-61, 67, fig. 19 m (1904). 



Betula ckinensis, var. Delavayi Schneider, III. Handb. Lauhholzk. II. 884 (pro 

 parte) (1912). 



Western Szechu'an: Mupin, alt. 2400-2900 m., side of streams, 

 October 1910 (No. 4382; small tree, 8-10 m. tall, girth 0.6-1-2 m.; 

 fruits); Tachien-lu, May 1904 (Veitch Exped. No. 4493; shrub 3 m. 

 tall; flowers and remains of old strobiles); without exact locality, 

 forests, alt. 3600 m., June 1904 (Veitch Exped. No. 4491; shrub, 1.8 

 m. tall; flowers and old strobiles). Western Kansu: south of 

 Min-chou, Lotani, alt. 1900 m., TT. Purdom (No. 812; 1.5-3 m.). 

 Yunnan: '*in silvis ad Koutui supra Mo-so-yn," alt. 2800 m., 

 J. Delavay (No. 3725; ex Franchet et Burkill). 



* 



I have not seen the type of this species, but 1 have little doubt that the sr^^j" 

 mens mentioned above belong to B. Delavayi Franchet, whicn is an upright shrub 

 or small tree, and seems somewhat intermediate in character between B. Potanimi 

 Batalin and B. ckinensis Maximowicz, being probably most nearly related to the 

 former. 



