1926] Babcoel-Leslen : CJiromosomes and Taxoiiomie Eelationsliips 339 



that it may throw light on the origin of chromosomal differences in 

 Crepis. Further research on species hybrids is in progress and should 

 throw considerable light on problems of relationship within the genus. 



3. Differences in chromosome dimensions are found among the 

 species of this genus. We note especially (a) differences in size of all 

 the chromosomes; (&) similarity in size of mo»st of the chromosomes 

 and differences in others. If Youngia be omitted, there remains only 

 one species, C. bulhosa, having all the chromosomes smaller than is 

 usual for the genus. At present we have this species in a section by 

 itself, but its ultimate classification awaits further study. Of the three 

 species of type (h), in which certain chromosomes are much shorter 

 than is usual in the genus and the others are similar in size, C. neglecta 

 and C. parviflora are provisionally classified in Eucrepis, while C. 

 setosa is in Barkhausia. 



4. It is noted that certain species having similar chromosome sizes, 

 particularly C. tectorum and the vesicaria group (including taraxaci- 

 folia, Marschallii, and myriocephala), are classed respectively in 

 Eucrepis and Barkhausia. These facts may indicate either close 

 relationship between the two sections or that similar changes in the 

 chromosomes have taken place independently in the two groups. For 

 the present we favor the latter assumption. 



5. This study was undertaken partly for the purpose of testing the 

 cyto-ta:xonomic method in a genus favorable for such research. As the 

 work progresses we are becoming more and more impressed wuth the 

 value of this method, and it is our intention to extend it to include 

 as many species of Crepis as can be obtained and cultivated at 

 Berkeley. 



LITERATURE CITED 



Afzelius, K. 



1924. Embryologische und zytologisehe Studien in Senecio und verwandten 



Gattungeii. Acta Horti Bergiani, vol. 8, pp. 123-219. 

 Beer, E. 



1912. Studies in spore development. II. On structure and division of the 

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 Bentham, G., and Hooker J. D. 



1873. Genera Plantarum, vol. 2, pp. 513-515. London. 

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1851. Beitrjige zur Flora Deutschlands und der Schweiz. Heidelberg. 

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BOISSIER, E. 



1875. Flora Orientalis, vol. 3. Geneva. 



