66 



PLANTS 



cross-fertilization fails. Autogamy is secured in a great variety 

 of ways. Some of these are; by movements of the anthers, 

 by movements of the stamens or style, or both, by changes 

 in length of stamens or style, by changes in the corolla, etc. 



Fig. t,^. — The inflorescence of the dog-wood. The flowers are small and 

 greenish and occur in clusters. Beneath each group of flowers are four large 

 white bracts which take the place of the petals in making the inflorescence 

 conspicuous. 



145. Some plants develop seed from flowers which never open. 

 Such plants also produce blossoms under favorable conditions 

 and the cleistogamic flowers are to be regarded merely as a 

 special form of autogamy. The corolla is reduced and 

 other parts of the cleistogamic flower may differ from the 

 corresponding parts of the blossoming flower. 



