984 The Trees of Great Britain and Ireland 



Coast region have not yet been fully studied in the field. The following varieties 



are notworthy : — .. / o,- \ tr ^A 



I Var. cordtfo/ia, Kegel, in Bull Soc. Nat. Mosc. xxxvm. 401 (1865) ; Fernald, 



in Rhodora, iii. i73 (1901) ; Sargent, Silva N. Amer. xiv. 55, t. 724 (1902). _ 



Leaves distinctly cordate at the base, smaller than in the type. An alpine 



tree, moderate in size, scarcely exceeding 40 feet in height, which occurs on Mount 



Katahdin in Maine, on the White Mountains in New Hampshire, and in the 



northern Rocky Mountain region. 

 2. Var. kenaica. 



Betula kenaica, ■E^a.ns, Bot. Gazette, yiy^m. 481 (1899); Sargent, Silva N. Amer. xiv, 53, t. 7^3 

 (1902), and Trees N. Amer. 205 (1905). 



A tree in Kew Gardens, about 20 feet high, obtained from Dieck in 1891, and 

 said to be a native of Alaska, has been identified by Sargent with B. kenaica. 

 Judging from this specimen and the description given by Sargent, this species 

 is only a small-leaved variety of B. papyrifera, from which it cannot be separated 

 by any characters of importance. The branchlets are minutely pubescent and 

 slightly glandular. The leaves are about 2 inches long, with five to seven pairs 

 of nerves. The fruiting catkins are smaller than in the type, about an inch long, 

 with glabrous ciliate scales, the middle lobe of which is narrow, oblong, not much 

 longer than the rounded broad lateral lobes. The bark is like that of ordinary 

 B. papyrifera, but the white colour is slightly tinged with orange. 



Betula kenaica was discovered in 1897 by Dr. Evans in Alaska, in the Kenai 

 Peninsula, near Cook Inlet ; and was found on Kodiak Island by Coville in 1899. 

 It is described as being a small tree, only reaching 40 feet in height. It is probable ^ 

 that the variety extends south from Alaska through British Columbia ; and is a 

 form with small leaves growing on poor soil and in mountainous regions, while var. 

 Lyalliana, with large leaves, occurs at nearly sea-level in rich alluvial soil. 



3. Var. Lyalliana^ Koehne, in Beissner, Schelle, and Zabel, Laubholz- 

 Benennung, 55 (1903); Schneider, Laubholzkunde, i. 115 (1904)- 



Betula occidentalis, Lyall, in Journ. Linn. Soc. {Bot.), vii. 134 (1864) (in part) (not Hooker); 

 Sargent, in Bot. Gazette, xxxi. 237 (1901), Silva N. Amer. xiv. 57, t. 725 (1902), and Trees 

 N. Amer. 204 (1905) (not Sargent, in Silva N. Amer. ix. 65, t. 453 (1896)). 



Betula Lyalliana, Koehne, in Mitt. Deut Dend. Ges. viii. 53 (1899). 



This variety, which is considered to be a distinct species by Sargent, differs 

 from the type in the greater size of the tree, in the orange tint of the bark, and in 

 the larger leaves, which are thin and membranous in texture, and not so thick and 

 coriaceous as is usual in this species. The leaves are about 4 inches long and 3 

 inches broad, with seven to nine pairs of nerves, and are coarsely and doubly 

 serrate, broadly ovate, with a broad, truncate base and a slightly acuminate apex. 



' Specimens just received from trees cultivated in the Arnold Arboretum, U.S., labelled B. occidentalis, Sargent, and 

 B. kenaica, Evans, are so similar, that they cannot be distinguished even as varieties. This confirms the opinion that var. 

 kenaica and var. Lyalliana [B. occidentalis, Sargent) are merely geographical forms of ^. papyrifera, the differences in the size of 

 the leaves and fruiting catkins being due to soil and climate. Under cultivation in this country they maintain these differences. 



2 This name is preferable to B. papyracea, var. occidentalis, Dippel, Laubholzkunde, ii. 177 (1892), as the plant described 

 there is apparently var. grandis, Schneider, a cultivated variety which originated from the eastern form of the species. Cf. our 

 remarks on B. occidentalis. Hooker, given in p. 993. 



