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GROWTH AND DEVELOPMENT 

 OF THE INFLORESCENCE AND FLOWER 



Claude W. IVardlaw 



UNIVERSITY OF MANCHESTER 



The angiosperrns, estimated at some 250,000 species, are the most 

 highly evolved and numerically the largest and most varied division of 

 the plant kingdom. In particular, the inflorescences and flowers show 

 conspicuous morphological diversity. Notwithstanding the excellent 

 and comprehensive taxonomic investigations of the past 200 years, as- 

 sisted in more recent times by comparative ontogenetic studies, many 

 important phylogenetic relationships and other phenomena are still in- 

 adequately understood: the existence of "phyletic gaps" is just as big 

 a bugbear in the angiosperms as it is in the less highly evolved classes 

 of vascular plants. Also, in view of the materials available, our infor- 

 mation on causal aspects of floral morphogenesis is very scanty indeed. 

 It may well be that the sheer wealth of materials has tended to 

 discourage investigators, making it difficult for them to know which 

 topics to select and how and where to begin. Some drastic simplifica- 

 tion of outlook on this great and important group certainly seems to be 

 needed. This may perhaps be achieved by formulating and testing 

 hypotheses relating to major, common factors in floral morphogenesis. 

 The abundant evidence of parallel developments ( or homologies of or- 

 ganization), in families and genera not closely related, supports the 

 view that common morphogenetic factors and processes do exist, and 

 that attempts to discover them and to formulate concepts of wide ap- 

 plicability may be fruitful. The aim will be to investigate characteristic, 

 major organogenic developments in inflorescences and flowers, use be- 

 ing made of selected materials and of the ideas and techniques that 

 have proved of value in the study of the vegetative shoot apex. These 

 studies, which we hope will advance knowledge of physiological, 



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