STUDIES IN VARIATION OF RED CLOVER. 



BY EDNA C. PAMMEL AND CLARISSA CLARK, 



Variation in Trifolium pratense presents many interesting problems, 

 some of which have been under consideration during the past two 

 seasons by the contributors to this paper. 



General relationships between number of flowers in the head, and 

 number of seeds produced, the influence of soils, and seasons, com- 

 parative dimensions of the 'flowers, and of pollen grains, were the 

 particular features studied. 



The present paper records thesis work of Miss Edna Pammel in 

 determination of variation in number of flowers in the heads of red 

 clover, from four different soil areas, and the thesis study of Miss 

 Clark in variation in size of pollen grains; notes are included from 

 the work of Miss Emma Wennholz and Miss Vera Mills in variation in 

 number of clover flowers in heads miscellaneously collected, and from 

 the study of Miss Mildred Walls upon variation in length of flower 

 (stamen tube). 



Miss C. M. King rendered much assistance in arranging the ma- 

 terials of the paper, and in the preparation of the curves. 



A STUDY IN VARIATION IN NUMBER OF FLOWERS IN HEADS 

 OF RED CLOVER. 



Countings were made from first, second and third crop clover 

 on three different kinds of soil, alluvial, black loam, and black loam 

 underlaid with gravel. All material was gathered in in the vicinity 

 of Ames, and only well developed heads were counted. 



Tbe following formulae from Davenport's Statistical Methods have 

 been used in working out the mean, index of variability, the coefficient 

 of variability, and the probable error in each case. 



n 



where A^-mean or average, m=sign of summation, v ^magnitude of any class, f= 

 frequency, or number of variates in that class, and n=total number of variates. 



