PLANT COLLECTING IN CHINA. 23 



and the United States of America, — for example, the tulip tree 

 (Liriodendron), the sassafras, the coffee bean tree (Gymnoeladus), 

 and the lotus lily (Nelumbium). 



But perhaps even more remarkable than anything else in plant 

 distribution is the fact of the same species occurring in China and 

 Japan and in the Alleghanies, and nowhere else in between. 

 Dip/n/Ileia cymosa is an example of this. The eastern Asia form is 

 absolutely identical with the Alleghany form, showing no variation 

 though the two habitats are separated by 140° longitude! 



The explanation of this remarkable affinity is to be sought in 

 ancient glacial phenomena. There can be little doubt but that in 

 pre-glacial times the latitude around the present Arctic circle 

 enjoyed a w r arm temperate climate and that the land connection 

 between eastern Asia and America was complete. The homogene- 

 ousness of the Arctic flora is most marked and this lends support 

 to the hypothesis that the interchange between eastern Asia and 

 America took place in high northern latitudes. 



Conclusion. 



In the foregoing, largely by means of pictures, I have attempted 

 to give some idea of the marvellously rich flora of Central and West- 

 ern China. Though much work has been done it must not for one 

 moment be supposed that the Chinese flora is in any sense exhausted. 

 Large tracts of country and even whole provinces, such as Honan, 

 have never had a plant collected in them. When it is remembered 

 that in China every glen and mountain range possess plants peculiar 

 to themselves it will at once be understood that our subject is far 

 from being exhausted. It is, indeed, inexhaustible. 



My last expedition, recently concluded, w r as promoted by Prof. 

 C. S. Sargent in the interest of the Arnold Arboretum. As the 

 result of this expedition seedlings of nearly 900 different plants are 

 at this present moment growing in the nurseries of that institution. 

 Seeds and plants, too, have been distributed in a most liberal way 

 to ardent cultivators in this country and in Europe, in order that in 

 so far as is possible nothing may be lost. The hardiness of these 

 new introductions is the crucial thing. This must, of necessity 



