Betula 993 



B. fontinalis x B. papyrifera. There are two small trees in Kew Gardens, 

 with wide-spreading pendulous branches, which were obtained from Dieck in 1891, 

 and were said to be B. occidentalis from Alaska. One of these trees has firm, dark- 

 brown, shining bark like that of B. fontinalis ; while the other has white bark,, 

 peeling off in shreds, indistinguishable from that of B. papyrifera. The branchlets 

 are exactly similar to those of B. fontinalis. The leaves (Plate 269, Fig. 8) are 

 very variable and not precisely the same on both trees ; resembling those of 

 B. fontinalis in colour, but much larger and much thicker in texture ; 2 to 3 inches 

 or more in length, broadly ovate ; rounded, truncate, or cuneate at the base, 

 acute at the apex, coarsely serrate or toothed in margin, pubescent and gland- 

 dotted on both surfaces. The fruiting-catkins (Plate 269, Fig. 8) and the scales 

 are as large as those of B. papyrifera ; but the scales are more like those of B. 

 fontinalis in shape, the three lobes being almost triangular, glabrous, and ciliate. In all 

 probability these two trees, with such variable characters in the bark and foliage, 

 are hybrid between B. fontinalis and B. papyrifera, which occur in the same region. 



The small-leaved birch, described above under the name B. fontinalis, was 

 identified by NuttalP with B. occidentalis, W. J. Hooker, Fl. Bor. Amer. ii. 155 

 (1839); and most botanists, including Sargent^ in 1896, Winkler, and Schneider, 

 have followed Nuttall. Sargent,^ however, in 1901 advanced the opinion that the 

 tall, large-leaved birch of the lower Fraser River, considered by us to be B. 

 papyrifera, var. Lyalliana, is a distinct species, which he identified with Hooker's 

 B. occidentalis ; and he proposed the name B. fontinalis for the small-leaved birch. 



The material* in the Kew Herbarium, on which Hooker founded his species, 

 includes no less than three distinct birches, none of which, however, is the large- 

 leaved variety of B. papyrifera ; and as his description is confused and not confined 

 to a single species, the name B. occidentalis. Hooker, must be entirely abandoned ; 

 and, in consequence, B. fontinalis is rightly adopted for the small-leaved birch, as 

 being the first valid name for this species. 



B. fontinalis is a small tree or spreading shrub, widely distributed in western 

 North America, where it usually grows on moist soil near the banks of streams in 

 mountain valleys. It extends from the basin of the upper Fraser and Peace rivers 

 in British Columbia, Alberta, and the valley of the Saskatchewan, southwards to 

 Mount Shasta and the northern Sierra Nevada in California, and through the Rocky 

 Mountains and the interior ranges to Nevada, Utah, and northern New Mexico ; 

 extending eastwards in the United States to the Black Hills of Dakota and north- 

 western Nebraska. Mr. M'Innes, of the Canadian Geological Survey, has recently 

 discovered this species in the district north of Lake Superior.^ 



1 N. Amer. Sylva, i. 22 (1842). ' Silva N. Amer. ix. 65 (1S96). ^ Bot. Gazette, xxxL 237 (1901). 



• This material includes : — 



I. One specimen collected by Dr. Scouler, labelled "De Fuca Straits"; another, collected by Dr. Tolmie, 

 "N.-W. Coast"; and a third collected by Douglas "west of the Rocky Mountains." These three specimens are a small- 

 leaved variety of B. papyrifera, identical with B. kenaica, Evans. 



II. Two specimens, collected by Dr. Richardson, labelled "Arctic Sea-Coast," one of which is B. fontinalis, Sargent ; 

 and the other, B. alaskana, Sargent 



III. A specimen, with young foliage, collected by Drummond, near Edmonton, which is probably B. fontinalis. 

 6 Canadian Forestry Journal, 1905, 175. 



IV 2 



