960 The Trees of Great Britain and Ireland 



arranged alternately. The leaf-scars, semicircular or crescentic, and three-dotted, 

 have on each side a linear stipule-scar. The pith of the twigs is oblong in section. 



About thirty species of Betula are known, all natives of the northern hemisphere, 

 extending from the Arctic circle to Texas in the New World, and to southern 

 Europe, the Himalayas, China, and Japan in the Old World. A considerable 

 number are shrubs, the treatment of which does not come within the scope of our 

 work. Of the arborescent species, a few, either not introduced or imperfectly known, 

 are not included in the following account. 



B. corylifolia, Kegel et Maximowicz, though not yet introduced, is included 

 in the key and fully described below, as it is very distinct and has been much 

 confused with other Japanese species. 



There are young plants in the nursery at Kew, received from the Arnold 

 Arboretum, as B. globispica, Shirai,^ which appear to be a very distinct species ; but, 

 as there is no authentic material in the Kew Herbarium with which to compare them 

 and ascertain if they are correctly named, it is unadvisable to deal with this species 

 at present. 



Similarly, young plants of B. alnoides, Buchanan-Hamilton, var. pyrlfolia, 

 Franchet, growing at Coombe Wood, which were raised from seed sent from central 

 China by Wilson in 1901, are left undescribed, as they show considerable variation, 

 and we cannot be certain, until they have borne fruit, of their identification. 



Key to Arborescent Species of Betula in Cultivation 



I. Branchlets and leaves quite glabrous. 



1. Betula verrucosa, Ehrhart. Europe, Northern and Eastern Asia. See p. 966. 



Leaves bi-serrate, shortly acuminate. 



2. Betula populifolia, Marshall. North America. See p. 987. 



Leaves lobulate and irregularly serrate, ending in a long caudate acumen. 



II. Branchlets or leaves or both pubescent. 



* Leaves cordate at the base. 



3. Betula Maximowiczii, Kegel. Japan. See p. 976. 



Leaves 5 or 6 inches long, broadly ovate. 



4. Betula ulmifolia, Siebold et Zuccarini. Japan. See p. 979. 



Leaves, 3 inches long, narrowly ovate. 



** Leaves cuneate at the base. 



5. Betula pubescens, Ehrhart. Europe, Northern Asia, Greenland. See p. 962. 



Leaves light green beneath, rhombic-ovate, bi-serrate, with six pairs of nerves. 

 Branchlets not glandular, clothed with minute dense erect pubescence. 



6. Betula davurica, Pallas. Manchuria, Korea, North China. See p. 974. 



Leaves light green beneath, narrowly ovate, bi-serrate, with six to eight pairs 

 of nerves. Branchlets glandular, with minute erect pubescence interspersed 

 with a few long hairs. 



' The Japanese name of this species, according to Matsumura and Goto, hjizo-kamba. 



