128 Moore: The study of winter buds 



1906, it IS probable that In Bettda popnlifolia the full number of 

 leaves, five to eight in terms of nodes, does not exist in the bud dur- 

 ing the winter. Two well-formed leaves are readily distinguished, 

 but the rest of the bud is a gelatinous mass from which only one 

 or two leaf-like bodies can be extricated. When the bud unfolds, 

 the two well-formed leaves expand at once but the rest of the bud 

 undergoes an exceedingly slow development, during which period 

 it is probable that new additions of leaves are made. 



In Ulmiis americana^ in Tilia vulgaris^ and in Almis hicana^ the 

 leaf content caiinot be determined with any reasonable degree of 

 accuracy beyond the fact that a large proportion if not all of the 

 leaves which unfold are present during the winten The irregu- 

 larity in the number of leaves and nodes renders a comparison of 

 these quantities valueless. The answer to this question, as in the 

 other doubtful cases, must be sought in a microscopic study of 

 the development of the buds from the beginning of the swelHng 

 period in April and May to the end of leaf expansion in summer. 



To summarize briefly, the full number of leaves which unfold 

 in the spring exists in the winter buds of Acer platanaides, Aesctdus 

 Hippocastannm^ Fagus americana^ Fagns sylvatica, Fraximis 

 americana, Liriodendron Tidipifera^ Hicoria ovata^ Philadelphiis, 

 Pice a excelsa, and Populus tremuloides. In Syringa vulgaris the 

 full number may or may not exist. In the last case, the number 

 probably developed in the spring does not exceed one or two pairs 

 of leaves, which soon die when the meristematic point ceases to 

 function. Although the number of leaves in the bud approaches 

 the number characteristic of this species there still remains an 

 element of doubt in the following: RJiododoidron maximum, 

 Quercus alba^ Uhmts americana, Tilia vidgaris, and Almis incana. 

 New additions of leaves probably take place in Betula popnlifolia, 

 m Salix fragilis, and in Salix alba. 



Measurements of buds : It is a striking coincidence that those 

 winters during which observations on the size of the bud have 

 been carried on have been winters of extraordinary mildness. 



Askenasy 



on the growth of the 



flower buds of cherry extend over a period of three years, says: 

 ** It is an important fact that greater warmth in winter exercises but 

 little influence on the growth of cherry buds. However, when 



