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A TEXTBOOK OF THEORETICAL BOTANY 



Fig. 12 1 2. — Phmtago media. Inflorescence showing 



protogyny. Upper flowers with long stigmas, 



lower flowers with long stamens and versatile 

 anthers. 



B. Homodichogamy (Errera). Some individuals are autogamous, 

 others dichogamous. Ajuga reptans. 



C. Heterodichogamous. Some individuals are protandrous, others 

 are protogynous. Juglans. 



III. Chasmocleistogamy (Delpino). Flowers are hermaphrodite, but some 

 are chasmogamous and some cleistogamous. Viola, Oxalis, and many 

 other examples. 



Direct autogamy stands somewhat apart from other methods of pollina- 

 tion because it involves only the internal arrangements in the flower itself 

 and is not dependent upon visitors. It seems paradoxical that autogamy 

 should take place at all, considering the extraordinary variety and abundance 

 of the contrivances which exist to promote allogamy. There can be no 

 doubt that allogamy has certain important advantages, but this does not 

 mean that autogamy is excluded and it very often happens that both events 



