Var. nipponica,’ Maximowicz, Me. Biol. xii. 923 (1888). This differs from the type in the branchlets not being so densely glandular, and in the longer, narrower cones, which are cylindrical, 1½ inch long, and ½ inch in diameter. This variety was found by Maximowicz in the Nikko mountains, and is probably the form of the species occurring in the main island of Japan.
B. Ermani is widely distributed in eastern Asia, occurring in Kamtschatka, Manchuria, Korea, Saghalien, Kurile Isles, and Japan. According to Komarov,’ it grows in Manchuria, near the sea-coast, from the river Amur to St. Olga Bay, in the Sichote-Alin mountains, in the north-eastern part of the province of Mukden, and in the Korean main range; and is a native of mountain forests at elevations between 2000 and 7000 feet. Komarov informs us that it is the largest of the birches, which he found in Manchuria, attaining a height of 60 to 100 feet.
According to Sargent,’ it is the most common birch in the high mountains of the main island of Japan, where it is scattered through the coniferous forests at 4000 to 6000 feet, and is very conspicuous from the white bark of the trunk, and the bright, orange-coloured bark of the principal branches. It appears to be the birch figured and described by Shirasawa,‘ as Betula alba, var. communis (not Regel), which he states to be a tree of vigorous growth, attaining 70 feet in height and 3 feet in diameter, occurring in the central chain of Honshu, especially at Shimot- suke, in Nikko, Musachi, in Chichibu, and Kiso, in Shinano. At Kiso the bark is used as material for writing on, and for envelopes; and also for torches, as it contains a considerable amount of resin. Elwes saw a birch, which he believes to be B. Erman, growing in great abundance in the forest north of Asahigawa, and also on the volcanic cone near Lake Shikotsu, in Hokkaido. Here it seemed to be commoner than, but not so large, a tree as B. Maximowiczii.
This species was introduced into cultivation through the agency of the St. Petersburg Botanic Garden; and is not uncommon in gardens both on the Continent and in England, where it is often wrongly named B. ulmifolia, B. corylifolia, etc. At Kew there are small trees, 20 to 25 feet in height, both of the typical form and of var. nipponica. The former® is the first of the birches to come into leaf, the foliage often being fully developed at the end of March; and, in conse- quence, the trees are usually much injured by spring frosts. The largest tree we have seen of this species is in the arboretum at Westonbirt, and when measured by Elwes in 1908, was 51 feet by 2½ feet. There is a good specimen apparently of the typical form at Benmore, in Argyleshire, which is grafted near the ground, and has yellowish scaly bark like that of B. lutea. In 1907 Elwes found it to be about 40 feet by 3 feet. Var. nipponzca is later in leafing, and is not usually injured by frost. Two trees of this variety at Grayswood, Haslemere, are about 30 feet in height. (A.H.)
1 This variety appears to be identical with a specimen in the Kew herbarium collected by Tschonoski on "high mountains not far from Fuji-yama,” which is labelled B. Bhojpattra, var. subcordata, Regel, in DC. Prod. xvi 2, p. 177 (1868).
2 Flora Manshuria, ii, 50 (1903).
3 Forest Flora of Japan, 62 (1894).
4 Icon. Essences Forest. Japon, text 42, t. 21 ff. I-15 (1900). Betula alba, var. communis, Regel, is B. papyrifera, an American species, which certainly does not occur wild in Japan.
5 The trees of the typical form were raised from seed sent by the Arnold Arboretum in 1893.
