xxii A NATURALIST IN WESTERN CHINA 



Castanea is more important in the number of species in eastern 

 continental Asia than in North America, but it is doubtful if any 

 Asiatic species is anywhere as common or forms such a large part 

 of the forest as the American Castanea dentata Borkh. forms on 

 some Appalachian slopes ; and in height and girth of trunk this 

 American tree has no Asiatic rival. In eastern North America 

 there are two other species ; of these one is a small tree or shrub 

 and the other a shrub, both bearing a single nut in the involucre. 

 In Western China there are also two species with similar fruit, but 

 one of these, Castanea Vilmoriniana Dode, is a noble tree and 

 the largest of the eastern Asiatic Chestnuts ; the other is a small 

 shrub, to be compared with the American Castanea nana Muhl. 

 The Japanese Cas/awea crenata S. and Z. reaches Korea, and Castanea 

 mollissima Blume, another small tree, ranges from the neighbour- 

 hood of Peking to the mountains on the Thibetan border. Cas- 

 tanopsis, which is related closely to Castanea, has its headquarters 

 in south-eastern Asia, with several species in southern China, 

 and one in California, but no representative in eastern North 

 America. It is possible that the number of species of Quercus is 

 greater in eastern continental Asia than in eastern North America. 

 Oak trees, however, are much less widely distributed in the former 

 region and are not numerous at the north, the Chinese Oaks being 

 chiefly confined to the southern provinces and usually evergreen. 

 Some of these evergreen Oaks should be referred to Pasania, 

 distinguished from the true Oaks by the arrangement of their flowers 

 in bisexual aments, the pistillate in several-flowered clusters below 

 the staminate, like the flowers of Castanea and Castanopsis. As 

 has been already stated, there are no Black Oaks in China, and 

 no species which are counterparts of the eastern American Chestnut 

 Oaks. The northern White Oaks are inferior in size to several 

 of the White Oaks of eastern North America, and it is doubtful 

 if any of the southern evergreen species equal in size Quercus 

 virginiana Mill., the Live Oak of the southern United States. 



ULMACEiE. — No Elm tree of eastern Asia equals the so-called 

 American Elm {Ulmus americana L.) in size and beauty, but it is 

 probable that the genus Ulmus has a larger representation of 

 species in western continental Asia than it has in eastern North 

 America, although it is still impossible to speak with much know- 

 ledge of Chinese Elm trees, which are very imperfectly understood. 

 It is interesting that the section of the genus (Microptelea), which 

 flowers in the autumn, has representatives in the two regions, 

 two in eastern America and one in China, the only other species 



