76 OUTLINE OF PLANT GEOGRAPHY 



shrubs and herbaceous plants having a similar distribution. 

 Witch hazel (Hamamelis), Sassafras, Virginia creeper (Ampe- 

 lopsis), bittersweet (Celastrus), honey-locust (Gleditschia) Hy- 

 drangea, Wistaria, mandrake (Podophyllum), moon-seed (Meni- 

 spermum), are a few of these, Asiatic-American genera. 



All of the European genera of conifers occur in China, and 

 there are several genera peculiar to China and Japan. Among 

 these Cryptomeria, Sciadopitys, Cunninghamia, Glyptostrobus, 

 and the Yew-like Cephalotaxus. Another of the Yew-family, 

 Torreya, has two species, two others being found in California 

 and Florida. 



The most peculiar tree, however, is the Ginkgo, a single 

 species which is the only survivor of a very primitive type which 

 flourished in the early Mesozoic. This tree, like the "Tree of 

 heaven" (Ailanthus), and the white mulberry, is sometimes 

 seen in the United States, where it seems to be quite at home, 

 as do many ornamental plants, like Wistaria, Forsythia, Weigela, 

 Daphne, peony and other ornamental garden shrubs and her- 

 baceous plants. 



China and the temperate Himalaya seem to have been the 

 centre of development of the rhododendrons and azaleas, of 

 which China is said to possess over a hundred species, compared 

 to four in all of Europe. The wetter regions, especially in the 

 south, are extraordinarily rich in ferns, and the warmer parts 

 have many species of bamboos. 



China is supposed to be the original home of the peach, forms 

 of which occur wild, and it is possible that the orange is the 

 product of one of the wild species of Citrus which are found 

 in southern China; but the different citrus fruits have been so 

 long in cultivation, that their origin is very uncertain. 



While most of southern and central China has usually an 

 adequate rainfall, the northwest portions merging into Mon- 

 golia are arid, and much of the country is a dry steppe or even 

 desert, with an extremely severe climate exhibiting great extremes 

 of heat and cold. Indeed all of China has a pronounced con- 

 tinental climate. 



Many of our choicest garden plants have come from China. 

 A Chinese rose, R. Chinensis, crossed with other species has 

 furnished the tea roses, and many others, and the fine climbing 



