6 MASS. EXPERIMENT STATION BULLETIN 402 



All the flower buds within a terminal bud may be killed without injury to the 

 embryonic leaves or to the apex of the stem axis within the terminal bud. In 

 this case, the new growth of the uprights develops as usual except that there are 

 no flower buds although vestiges of them may be found by examination with a 

 hand lens. Sometimes evidence that flower buds had been formed is shown by 

 the presence of the pedicels, each bearing two small leaves (bracts) at its summit 

 with a very small dead structure between them representing a flower bud killed 

 very early in its development. 



Injury which does not kill all or most of the embrj^onic leaves within a terminal 

 bud may kill small areas of tissue within individual leaves varying from a few 

 cells up to half a leaf. Portions of leaves remaining uninjured continue their 

 development when the terminal bud begins active growth in the spring, but the 

 leaves developed therefrom are then more or less deformed (Fig. 2). Apparently 

 all or most of the flower buds are killed when embryonic leaves are injured in 

 this way. 



Figure 2. Uprights from Vines of the Howes Variety from a Bog near Waquoit Massachusetts 

 showing severe injury to the new leaves caused by a lack of dissolved oxygen in the water diving 

 the preceding winter-flooding period. Water was held late. Most of the flower buds were killed 

 at a very early stage of their development; two buds on the upright at the extreme right made 

 some growth but died before blossoming. Collected June 29, 1937. X 1. 



Incompletely differentiated flower buds may be injured but not killed imme- 

 diately. These buds continue their development for some time but die sooner 

 or later; the more severely injured ones die at early stages of growth, those less 

 severely injured die later, very often developing into flowers which fail to set 

 fruit. This delayed efi^ect of injury shown by the death of flower buds at various 

 stages of development before they reach the mature blossom stage is referred to 

 in Wisconsin as "flower bud absorption." 



Some berries also die before they are one-fourth grown; others continue to 

 grow but never become large enough to be picked and the average size of the 

 berries that mature is often reduced. 



