7G CHINESE ECONOMIC TREES 



BETULA 



Trees or shrubs. Bark with conspicuous lenticels, often peeling in 

 thin, papery strips, frequently white. Lateral buds usually sessile, scaly 

 and pointed. Leaves deciduous, alternate, stalked, pinnately veined, 

 serrate or crenate or incised; stipules caducous. Flowers monoecious, 

 apetalous. Staminate catkins cylindric, naked, solitary or several 

 together, terminal or lateral, conspicuous in winter, flowering in spring 

 before or with the leaves. Flowers 3 to each scale; stamens 2, divided at 

 the apex; calyx 1-4 parted. Pistillate catkins from lateral scaly buds 

 developing with the leaves, the flowers of these catkins in 3's, without 

 calyx; ovary 2 celled, 1 ovuled; style 2, stigmatic at the tip. Fruit 

 cylindric or cone-like; scales 3 lobed, deciduous, falling with the winged 

 nutle.ts. Nutlets compressed with a more or less developed and often 

 transparent wing on each side and crowned by the remnant of the style 

 at the apex. 



About 35 species of birches are known, a considerable number are 

 shrubs. Probably 10 or 12 species occur in China. The birches are 

 widely distributed and occupy a great range of situations. Several 

 arborescent species are important forest trees producing a close-grained, 

 moderately hard wood which is esteemed for cabinet and furniture making, 

 interior finish and for small woodenware such as shoe lasts and spools. 

 It has a high fuel value. The bark is impervious to water and that of 

 several species is sometimes stripped from the tree in long sheets by the 

 American Indians and fashioned into light boats which they call canoes. 

 Boxes, shoes and boots are also made from the bark. The leaves and 

 bark yield a medicine. The sweet sap tapped from several species is made 

 into a pleasant beverage. 



The Chinese species of birches can be certainly known only after 

 extensive collections from various parts of the country have been made 

 and a comparative study undertaken. Species have been described by 

 European and American botanists based on fragmentary material out of 

 forms which are undoubtedly only geographical variants. 



Betula japonica Siebold. 



(B. alba Turezaninow.) 



(B. alba var japonica Rehder.) 



Small tree, 25 m. tall with glabrous, glandular or glandless branches. 

 Leaves broadly cuneate, truncate or rounded at the base, deltoid-ovate, 



