THE AMERICAN BOTANIST 



131 



This identification is accomplished by means of the leaf- 

 scar which in the white ash is shaped like a crescent with the 

 points up and partly surrounding the bud, while in the black 

 ash the scar is either straight across on the upper side or only 

 slightly curved, the two upper corners being round instead of 

 pointed, with the bud either entirely above the scar or only 

 slightly set in it. 



THE PRODUCTION OF NEW FORMS 

 IN RUDBECKIA 



By Willard N. Clute. 



"QLANT genera usually possess a good many characteristics 

 that are not taken into consideration by the systematist. 

 With him, form, size, structure, outline, and similar features 

 have the most weight, since by such characters he may most 

 readily distinguish one species from another or identify an 

 unknown specimen, but there are many less obvious peculiari- 

 ties in any closely related group of plants which may well 

 engage the attention of the student and prolong his interest 

 far beyond the identification stage of his botanical investiga- 

 tions. 



One of the most interesting of these lesser plant char- 

 acters is the brownish-red color that pervades the genus 

 Rudheckia, the group to which the coneflower belong. In 

 this genus, the ray flowers are normally yellow, but in many 

 cases the disk flowers have a tinge of brownish-red, which is 

 deep enough to be noticeable, and in our commonest species, 

 Rudheckia hirta, it is so prominent as to give a basis for the 

 common name, the plant being generally known as black-eyed 

 Susan. 



Though the brownish-red color of Rudheckia flowers is 

 not an exclusive famity peculiarity, it is so conspicuous in this 



