400 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



We will now turn our attention to a most interesting problem in 

 plant distribution, namely, the affinity which exists between the flora 

 of China and that of North America, and more particularly of the South- 

 Eastern Atlantic States. 



Oue of the most remarkable results of the extension of our knowledge 

 of the Chinese flora has been the discovery in the heart of China of 

 representatives of genera originally known only from the Atlantic side 

 of the U.S.A. Indeed the headquarters of many genera originally only 

 known from the Southern States of U.S.A. is now known to be China. 



The genus Podophyllum illustrates this : the first known species was 

 P. pdtatum from America ; now we have P. Emodi from the Himalaya 

 and W. China, P. pleianthum from Formosa, P. versipeUe from South 

 China (Canton), and two new species in Hupeh, and another in W. China. 

 Magnolias also afford a good illustration of this remarkable affinity. 

 The genus is absent from Europe and Western North America, and is 

 represented by six species on the Atlantic side of U.S.A. and eleven 

 species in China and Japan. 



Several genera are represented by one species each in China and 

 South-Eastern U.S.A. 



China. 



Liriodendron chinensis. 

 Gymnocladus chinensis. 

 S tylop horum japonicum, 

 Nelumbium speciosum. 

 Dccumaria sinensis. 



United States of America. 



Liriodendron tulipifera. 

 Gymnocladus canadensis. 

 Stylophorum dip hy Hum. 

 Nelumbium luteum. 

 Dccumaria barbara. 



But even more remarkable than either of the foregoing facts is the 

 occurrence of the same species oilplants in China and Japan and in 

 the Alleghany Mountains between Virginia and Georgia (South-Eastern 

 U.S.A.) and nowhere else between. Diphyllcia cymosa is one such, and 

 no variation is to be seen between the two forms, although they are 

 separated by 140° longitude. Sassafras Tzumu occurs only in China 

 and South-Eastern U.S.A., and has similar medicinal use in China and 

 the States, although separated by 150° longitude. 



The outstanding features of the Chinese flora may be thus sum- 

 marised : — 



(1) Its richness, particularly in flowering trees, shrubs, herbaceous 

 and alpine plants eminently suitable for outdoor cultivation in Great 

 Britain. 



(2) It is the home of the parents of many of our best known garden 

 plants. 



(3) The complete absence of the Broom (Cytisus), Gorse (Ulex), 

 Heather, and the Rock- rose family. 



(4) The border line of China and India, that is, the Tibetan-China- 

 Himalayan region, is the headquarters of that wonderful flora which 

 extends from Afghanistan to the Yellow Sea and southwards to Malaya. 



(5) The Chinese flora proper is distinct from the floras of Japan and 

 Korea, which have affinities with that of Siberia. 



(6) The close affinity between the flora of China and that of the 

 Atlantic States of the U.S.A. 



