Moore: The study of winter buds 141 



summer and autumn are in many cases well organized at the ap- 

 proach of winter. 



The leaf buds of all deciduous and evergreen trees and shrubs 

 investigated enter upon a winter resting period, the duration of 

 which varies in the different plants. 



mi 



little influence on the growth of leaf buds. Flower buds respond 

 more quickly to the influence of continuous high temperatures. 



Of the species under investigation, some leaf buds show no 

 change either in length or in diameter until February or March ; 



May 



M 



at lower temperatures than prevail during the preceding winter 

 months. 



Organization of additional tissues does not take place within 

 the leaf buds during the winter but becomes apparent in March or 

 April. A stretching of cells occurs in the meristematic region of 

 some species as early as December and January, and manifests itself 

 by a greater convexity of the meristematic surface. This change 

 is microscopic and produces no change in the external appearance 

 of the buds. 



i 



The first apparent evidence of growth is a swelling of the closely 

 compacted tissues. With continuous high temperatures rapid and 



vigorous growth follows. 



The leaf buds of the two evergreens investigated, FUea and 

 Rhododendron, exhibit the longest rest period. 



For valuable aid and supervision in carrying on this investiga- 

 tion most grateful acknowledgment is given to Dr. Margaret C. 

 Ferguson, of Wellesley College. 



Bibliography 

 Askenasy, E. Ueber die jahrliche Periode der Knospen. Bot. Zeit. 



35: 789-847- P^' 4' '877. 

 Bailey, L. H. Lessons with plants. 1-498. New York, 1898* 



Baranetzky J. Eine Mittheilung iiber die Periodicitat des Blutens^bei 



den kraulartigen Pflanzen und deren Ursachen, Bot. Zeit. 31 : 65 



-76. 1873. 

 Busch, I. Untersuchungen fiber die Frage ob das Licht zu den unmit. 



telbaren Lebensbedingungen der Pflanzen oder einzelner Pflanzen. 



organe gehort. Ben Deuts, Bot. Ges. 7: (25). 1889, 



