
NOTE ON VARIATION IN THE RAY FLOWERS OF 
RUDBECKIA.! 
RAYMOND PEARL. 
IN a recent number of this journal (Vol. XX XVIII, pp. 427- 
429) Mr. F. C. Lucas has published an account of the variation 
in the number of ray flowers in Rudbeckia hirta, the common 
*brown-eyed Susan." Since attention has been called to the 
matter in this way, it seems desirable to put on record some 
statistics on variation in this form collected by the writer. 
My material consisted of 430 heads from plants collected at 
random from a large patch, July 25, 1903. The locality was 
Farmington, N. H. The plants were growing in an open hay 
field, on a moderately sloping hillside. The soil was a sandy 
loam, and on account of the thorough drainage, the ground was 
decidedly dry. In the counting I was assisted by Mr. Roswell 
J. Pearl. 
The following frequency distribution of ray flowers was 
obtained : 
Number of : 
ray flowers. 6 9 8 910 JI HM 114 'S 16 17 18 19 20 21 22 23 24 
Pay sopd eup Donare? 
Total. 430 
The frequency polygon is shown in Figure 1. 
The mean number of ray flowers here is 11.365. The agree- 
ment with Lucas’ Lot 4 is very close in all particulars except €x- 
tent of range. This series gives peaks at the Fibonacci numbers 
8 and 13, the principal one being at 13, as in his cases. In this 
series, as in Lucas’ Lots 2, 3, 4 and 5, all the heads on each 
plant collected were counted. It would appear from a compari- 
! Contributions from the Zoölogical Laboratory, University of Michigan. No. 
87 
