PREFACE 



This study was begun in the autumn of 1909. It has been carried 

 on continuously under glass during two winters', and outdoors in the 

 summer of 19 10. A collection of the obtainable species of Lathyrus, as 

 well as a very extensive collection of the varieties of sweet peas, was grown 

 at Ithaca. In addition to the above the writer was enabled to study the 

 exhibits of outdoor-grown sweet peas at the annual exhibition of the 

 National Sweet Pea Society at New York in July, 19 10, and of the winter- 

 flowering varieties at Boston in March, 191 1. 



The investigation was begun with a view of studying the various species 

 of Lathyrus for the purpose of monographing them, and particularly of 

 determining their value as ornamental plants. The studies on s-^eet peas 

 included the evolution of the flower, as well as the preparation of careful 

 descriptions and the detection and elimination of synonyms among pres- 

 ent-day varieties. The descriptions of the garden varieties will appear 

 in a later publication; those of winter-flowering varieties are included in 

 Bulletin 319 of this station. 



The author wishes to extend his thanks and grateful acknowledgments 

 to Professor John Craig, who has given great encouragement, kindly 

 advice, and all possible facilities for carrying on the investigation; to the 

 National Sweet Pea Society for their cooperation in the variety tests; 

 to the United States Department of Agriculture for seeds of species of 

 Lathyrus; and to the seedsmen of the United States and Great Britain 

 who contributed seeds for the trials. Among the latter, mention should 

 be made of the assistance rendered by Messrs. C. C. Morse & Co. in 

 contributing a collection of seventy-two varieties, representing various 

 types and old or obsolete varieties, for the study on the evolution of the 

 sweet pea. 



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