986 The Trees of Great Britain and Ireland 



5. A hybrid between B. papyri/era and B. populifolia, found growing wild in 

 New Hampshire and Massachusetts, is described by Sargent in Garden and Forest, 

 viii. 356, fig. 50(1895). 



Several varieties and hybrids have originated in cultivation : 



6. Var. grandis, Schneider (B. macrophylla, Hort.). Leaves large, cordate, 

 lobulate in margin. Similar leaves appear on coppice shoots and on lower branches 

 of old trees belonging to the typical form of the species. 



7. B. Koehnei, Schneider, Laubholzkunde, i. 114 (1907), a hybrid between B. 

 papyrifera and B. verrucosa, is identical with B. cuspidata of Spath's nursery. 



8. B. excelsa, Aiton, Hort. Kew, iii. 337(1789), long supposed to be either a 

 distinct species or a cultivated variety of B. papyrifera, is considered by Schneider 

 (op. cit. 108) to be a hybrid between this species and B. pumila, and differs from the 

 former mainly in the smaller size of the leaves. 



Distribution 



The paper birch is the most widely distributed species of Betula in North 

 America, the typical form extending northward to Labrador, the southern shores of 

 Hudson's Bay and Great Shore Lake, and southward to Long Island, New York, 

 northern Pennsylvania, central Michigan, central Ohio, northern Nebraska, the 

 Black Hills of Dakota, and northern Montana. In various forms it also occurs 

 west of the Rocky Mountains to the Pacific Coast, in Alaska, British Columbia, 

 Washington, and Idaho. 



It usually grows on rich wooded slopes and on the borders of streams, lakes, 

 and swamps ; and is common in Canada, New York, and northern New England, 

 becoming rarer to the southward and in the Rocky Mountains. (A. H.) 



Cultivation 



Notwithstanding the rarity of this tree in cultivation, it seems to grow freely 

 at Colesborne, where I have raised it from seed, and planted it out in situations 

 where it is exposed to cold and damp. Here it does not suffer from spring frost, 

 and has attained 15 feet in height in seven years. As an ornamental tree, however, 

 it is not in England superior to the common birch, and has no special merit to 

 justify its being planted except as a curiosity. 



The paper birch was introduced into England in 1750, according to Loudon; 

 but is rarely seen except in botanic gardens, as at Kew, where there are several 

 fair-sized specimens, the largest, a tree with ascending branches, near the Victoria 

 gate, being 45 feet high by 3^ feet in girth. Close to it is another nearly equal in 

 size, with markedly drooping branches. In the Cambridge Botanic Garden, a tree, 

 grafted at \\ foot from the ground, was, in 1906, 47 feet by 4 feet 7 inches. 



The largest tree we know of in cultivation is in Mr. Kaufman's garden at 

 White Knights, near Reading, which Henry measured in 1904 as 82 feet by 4 feet 

 1 1 inches. Another tall white-barked tree with a clean stem, grafted on common 



