28 



In general the whole chart shows a wide range of variation 

 for most of the species. Perhaps this is not unexpected for this 

 rather severe climate but when the correlation between the 

 recorded mean temperatures and the first flowering is as plainly 

 shown as by the seasons 191 7 and 1921, if not by others, it 

 seems probable that temperature is the chief controlling factor. 



Department of Biology 



Dartmouth College. 



A CASE OF PISTILLODY AND STAMINODY 

 IN THE PLUM. 



BY HAROLD B. TUKEY 



This past season in a variety of cultivated plum, probably 

 (Pruniis triflora) x (P. triflora x Simonii), a queer case of pistil- 

 lody of the stamens and staminody of the petals occurred. 

 These are not unusual phenomena but, as they are most often 

 reported, one whorl of floral parts is entirely and uniformly 

 replaced by another. In this case, however, there was more 

 or less of a gradation from one member to another within the 

 different whorls. 



Normally the flowers of the plum {Pruniis spp.) are arranged 

 after this fashion: A single pistil, bearing one style and one 

 stigma, at the bottom of a cup-shape receptacle on the edge 

 of which are five sepals, five petals, and fifteen to many stamens- 

 the petals alternate with the sepals. Fifty per cent of the flowers 

 on the trees of this variety were so arranged, but the other 

 fifty per cent presented a host of variability. 



Frequently the stamens were replaced by pistils and when 

 this was the case the pistils were either five in number and 

 alternate with the petals or ten in number in five groups of 

 two, likewise alternate with the petals. On the inner side of each 

 of these pistils from the stigma to the base of the ovar\' ran a 

 distinct suture, so that their appearance was that of what might 

 be characterized as "introrse pistils," a name which is seen to 

 be more appropriate when it is said that normally the pistils 

 dehisced along this line and aborted the ovule contained within 

 the o\'arv. 



