Morphology of Flowering • 5 



ogy of flowering have been more concerned with the conditions 

 bringing about the production of flower primordia— with flower 

 initiation, as it is called— than with subsequent flower development, 

 although in practice both are studied. 



-■ — 



B 



D 



Fig. 1-1. Intermediate conditions between full flowering and vegetative habits 

 in Kalanchoe blossfeldiana, from (A) normal, fully developed inflorescence through 

 (B)-(D) increasingly vegetative forms, to (E) a fully "vegetative inflorescence" 

 in which there are no flowers at all, but a branching habit still unlike that in the 

 normal vegetative state. The sequence (A)-(E) reflects decreasing amounts of 

 short-day treatment. (Photographs from Harder [1948], by permission of the 

 company of Biologists, Ltd., and courtesy of Dr. R. Harder, University of 

 Gottingen.) 



A concept occasionally found in the experimental literature 

 is that of ripeness-to-flower. In the development of many plants 

 from seed, there may be a stage before which flower initiation can- 

 not occur, at least in response to conditions that would bring it 

 about in older plants. A plant which has passed this stage is said 



