460 WILSON EXPEDITION TO CHINA 



Bdula Wilsonii Bean in Kew Bull. Misc. Inform. 1914, 30 (1914); Trees & 

 Shrubs Brit. Isl. I. 264 (1914). 



Western Szech'uan: Wa-shan (not Wushan), alt. 2100-2S00 

 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 branchlets, 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 com.mon. Usually all its slender whiplike 

 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 Bat. XIII. 205 (1899).— 

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

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



Betula chinensis, var. Delavayi Schneider, III. Handb. Laubholzk. 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., W. 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 tjT^e of this species, but I have little doubt that the speci- 

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

 or small tree, and seem^s somewhat intermediate in character between B. Potaninii 

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

 former. 



