DEVELOPMENT OF VEGETATIVE 

 AND FLORAL BUDS 



RALPH H. WETMORE,! ERNEST M. GIFFORD, JR.,- 

 and MARGARET CORNETT GREEN ^ 



Biological Laboratories, Harvard University, Cambridge, 



Massachusetts 



In the higher plants, a bud is defined as an undeveloped state of a 

 main stem or a branch; it usually has embryonic leaves, some possibly 

 modified as protective scales. Whether a bud is terminal, axillary, or 

 adventitious, whether it is in vegetative or flowering phase, its distal 

 end is characteristically terminated by an apical meristem. This apical 

 meristem is of unique importance to the plant. It is known, for ex- 

 ample, that ( 1 ) its component cells are capable of cell division under 

 favorable conditions, thereby increasing the number of cells compris- 

 ing it and so adding to the length of the axis concerned; (2) leaf 

 primordia are produced in regular, orderly sequence from aggregates 

 of these newly produced cells; aggregates of cells of the apical meri- 

 stem in or above the axils of these newly formed leaf primordia 

 become the new bud primordia. The development of buds from these 

 primordia may be deferred until correlative relations between them 

 and the apex no longer interfere with their growth; (3) the apical 

 meristem and the young, derived leaves collectively are effective in 

 the induction of vascular tissues in the axis proximal to them. 



An examination of buds of various plants and in various states of 

 development shows that differences of pattern occur in their apices. 

 Stated briefly, a major conclusion is that they are constructed on no 

 single histological pattern (Wetmore and Wardlaw, 1951). While 



1 This work was supported in part by a grant from the National Science 

 Foundation to the senior author and Prof. K. V. Thimann. 



- This work was done while a Merck Senior Postdoctoral Fellow at the Bio- 

 logical Laboratories, Harvard University. 



3 Work on this research was completed while holding a Junior Fellowship 

 from the Canadian Federation of University Women at Radcliffe College. 



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