968 The Trees of Great Britain and Ireland 



cylindrical, on long, slender, minutely pubescent, glandular stalks ; scales long- 

 stalked, veined, puberulous, ciliate, with the triangular central lobe slightly longer 

 than the broad, rounded, recurved, lateral lobes ; nutlets with rather broad wings. 



This variety 1 is distinct in the larger number of nerves in the narrower, longer, 

 slightly pubescent leaves, which are simply serrate in margin ; and in the characters 

 of the fruit-scales. The bark of cultivated trees is more like that of B. Ermani than 

 the common birch, as it is uniformly white in colour, with raised whitish lenticels, 

 and scales off in transverse shreds. According to Sargent, 2 it is a slender tree, 

 attaining about 80 feet in height in Yezo. 



There are three trees of this variety in Kew Gardens, about 20 to 25 feet in 

 height, which were raised from Japanese seed sent by Sargent in 1891 under the 

 erroneous name B. ulmifolia. A similar tree, 8 25 feet high, cultivated at Kew as 

 B. alba, var. latifolia, was obtained from Madrid in 1887. These trees are narrowly 

 pyramidal in habit, and very ornamental on account of their beautiful white bark ; 

 and appear to be fast in growth and very thriving. 



4. Several varieties have arisen in cultivation, of which the most noteworthy are : 



Var. Youngi, Schneider, Young's weeping birch ; and var. elegans, Schelle, 

 Bonamy's * weeping birch. Both these forms have long, slender, pendulous branchlets ; 

 and are usually grafted on stems 6 to 8 feet high, when they assume the habit of 

 the weeping sophora. A fine specimen is growing in Smith's nursery at Worcester. 



Var. fastigiata, Schelle, is characterised by its upright branches, the tree 

 resembling in its appearance a Lombardy poplar. According to a writer in 

 Woods and Forests, this variety retains its foliage later in autumn than any other 

 form of the silver or common birch. 



Var. purpurea? Leaves purple, resembling in colour those of the purple beech, 

 valuable for ornamental planting. 



Distribution 



This species is widely distributed in Europe, and in northern and eastern Asia. 

 The northern limit, beginning in Scotland, crosses Norway in lat. 64, Sweden 

 in lat. 65, and ascends in Russian Lapland to Lake Ruanjarvi ; and thence, crossing 

 Lake Onega, passes through the province of Vologda to Siberia, where its exact 

 distribution has not been made out. In eastern Asia, var. japonica is met with in 

 Manchuria, Saghalien, and Japan. The type occurs in the mountains of north 

 China, and was found near Lake Kokonor (lat. 37 50') by Przewalski ; and it 

 appears to be the common birch in the Altai and Ural mountains. It is not found 

 in Persia or Afghanistan, but occurs on the higher mountains of the Caucasus and 

 in Armenia and Asia Minor. In Europe the southern limit extends from the 



1 The Japanese name for this variety is Shira-Kamba. * Forest Flora of Japan, 61 (1894). 



3 This tree has broadly ovate leaves, subcordate or rounded at the base, and larger than those of the trees raised from 

 Japanese seed, sent by Sargent ; but in other respects is identical, and is probably also of Japanese origin. 



* This originated in Bonamy's nursery at Toulouse, and is usually known in gardens as B. alba ptndula elegans. Cf. 

 Rev. Hort., 1869, p. 135, fig. 33, and Gard. Chron., 1869, p. 1278. 



6 Probably identical with var. atrosanguinea, stated by Schubeler to have originated in France, and to be growing in the 

 Botanic Garden at Christiania. (H. J. E.) 





