Betula luminifera Winkler

Synonyms

B. alnoides var. pyrifolia Burk.

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A tall tree, the younger branches bright reddish brown; young twigs covered more or less densely with pale hairs or down. Leaves ovate, 212 to 5 in. long, 112 to 312 in. wide, rounded or slightly heart-shaped at the base, pointed, unequally toothed, each tooth ending in an abrupt, slender point, ciliate, downy on both surfaces, dark dull green above, bright green beneath, covered with minute, lustrous resin-glands; veins nine to twelve; leaf-stalk 12 to 34 in. long, downy or nearly glabrous, reddish. The young, expanding leaves are of a pretty, red tinge. Fruiting catkins 112 to 312 in. long, cylindrical, 14 in. diameter, borne singly; scales very small, the middle lobe several times larger than the side ones. Wings of fruit about as broad as the nutlet.

This species is closely allied to the Himalayan B. alnoides (see below), but is a native of W. China; discovered by the French missionary Farges in E. Szechwan and introduced by Wilson in 1901 and again in 1907. According to Wilson it is the common low-level birch in Szechwan and Hupeh, found up to an altitude of about 8,000 ft and rarely more than 65 ft in height. Trees at Kew grew well and were curiously distinct in the resinous sheen beneath the leaves, which became more apparent as the leaf dried. They varied considerably in the downiness of the young shoots. The last of these died in 1960 when 46 ft high.

B. alnoides D. Don B. acuminata Wall., not Ehrh. – A tree to about 70 ft in the wild state, with a papery, greyish or brownish bark, peeling off in narrow, horizontal, silvery scrolls. A native of the Himalaya, longer known than B. luminifera, to which it is closely allied. It is reputed to be tender, but hardy forms might be found at the western end of its range in the Sutlej basin, where it ascends to 10,000 ft. It differs from B. luminifera in having the fruit-catkins in clusters of two or three.

B. cylindrostachya Lindl. B. alnoides var. cylindrostachya (Lindl.) Winkler – A species closely allied to B. alnoides. According to Dr Bor (Manual of Indian Forest Botany) it is quite distinct in the field owing to its coppery brown bark, which peels in long vertical flakes and, in India, is confined to the eastern end of the Himalaya and the Naga Hills. It is also found in Burma and Yunnan.

The above three species are, however, little known and might prove on further investigation to be states of a single wide-ranging species. They are the representatives on the mainland of E. Asia of the section Acuminatae, characterised by the long (112 to 4 in.), pendulous fruit-catkins, which, except in B. luminifera, are borne in clusters of two to four. The fourth, and best-known member of this group, is B. maximowicziana of Japan (q.v.).

Genus

Betula

Other species in the genus