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 aWTANICAi 

 QAkUfzN 



TORREYA 



Vol. 27 No. 3 



May-June 



THE FLORA OF YEZO (JAPAN) 



By T. D. a. Cockerell 



In the Japanese Journal of Botany, Vol. 2, No. 4 (1925) is an 

 extremely interesting analysis of the vegetation of Yezo, the 

 northern island of Japan, by Yushun Kudo of the Hokkaido 

 Imperial University. My first thought, on reading it. was, 

 how much it would have pleased Asa Gray. The full enumeration 

 of species, based on many years of collecting and study. The 

 tabulated lists showing their distribution elsewhere. The 

 ecological details, all together give us a picture of the flora in its 

 true relation to other floras of the northern hemisphere. Having 

 been in the coast region of Siberia opposite Yezo, and being 

 also more or less familiar with the boreal flora of America, the 

 paper is doubly interesting to me, so I venture to offer a few 

 comments. 



The known plants of Yezo, including the southern Kuriles 

 adjacent to it, include 597 genera and 1629 species. This 

 enumeration includes only flowering plants and pteridophytes. 

 The largest genus is Carex, with 107 species. In the Rocky 

 Mountains and adjacent plains, as shown in Rydberg's Flora, 

 Carex is also the largest genus, with 162 species. According 

 to Kudo's tabulation on p. 285, Viola is the next largest genus 

 in Yezo, with 32 species. There is some confusion here, as in 

 the complete list of species, we see only 13 names under Viola. 

 Turning over the page, we find the rest, catalogued by mistake 

 as Hypericum. The next largest genus is Polygonum (in the 

 broad sense), with 29 species; then comes Epilohium with 20. 

 The grasses have the greatest number of genera, 49. and 117 

 species. The Compositae are almost as numerous, with 116 

 species. There are 85 endemic species, if we include the Southern 



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