MEW YORK 



»*<>tank:al 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



AGRICULTURAL SCIENCES 



Vol. 2, No. 11, pp. 315-341, 7 figures in text March 6, 1926 



CHROMOSOME NUMBER AND INDIVIDUALITY 

 IN THE GENUS CREPIS 



II. THE CHROMOSOMES AND TAXONOMIC RELATIONSHIPS 



BY 



ERNEST BEOWN BABCOCK and MARGARET MANN LESLEY 



CONTENTS 



PAGE 



Introduction 315 



Material and methods 316 



Acknowledgments 316 



Taxonomy and cytology of twenty-one species of Crepis 317 



Literature and discussion 332 



Summary and conclusions 338 



Literature cited 339 



INTRODUCTION 



For the past three years we have been accumulating data on the 

 taxonomy and cytology of the genus Crepis. The present paper repre- 

 sents only two phases of our general project, which also includes exten- 

 sive genetic research on species and species hybrids, the whole under- 

 taking being an effort to establish a natural classification of a genus 

 which has been a source of considerable difficulty to taxonomists and 

 which presents a wide array of chromosome numbers. In addition to 

 number we have examined the size of the chromosomes in the species 

 studied, in the hope that this might also prove useful as a criterion 

 in classification. 

 -O We are confining our discussion to species which we have been able 



or> to cultivate in the greenhouse or garden and to identify with certainty, 

 1^ a procedure which has thrown considerable light on the classification. 

 <^ Ideally the taxonomist should know his species as they appear under 

 Ctf natural conditions, but obviously this is impossible for any one botanist 

 «^ in the case of such a large and widely distributed genus as Crepis. 



