214 MISSOURI BOTANICAL GARDEN. 





mate to conclude that the exserted condition is a factor of 

 importance in the development or permanence of the apically 

 dehiscent anther. Comparative evidence would suggest 

 that these forms with cylindrical or urceolate perianth are 

 not primitive, but of recent origin. The anthers seem to 

 open at first by a terminal gap and it may be that longi- 

 tudinal dehiscence has been reassumed bv these forms as a 

 result of the changes in the form of the perianth. 



Only a thorough knowledge of the living plants in their 

 own environment supplemented by histological studies will 

 decide some of these questions. 



Stemonoporus and Monoporandra differ in the structure 

 of the androecium from all other Dipterocarpaceae. 



In Begonia the perianth is patent in all forms. The 

 two apically dehiscent species of the section Solanthera 

 have more elongate anthers than many species of the genus, 

 but the distinction here is not a verv sham one. 



Gardneria seems 



the Loganiaceae. 



among 



h 



the structure of the apically dehiscent genera and many 



'tT> 



seems 



mo that Exacum and Cotylanthera depart markedly from 

 the type of the family. 



A long corolla tube is characteristic of most Solanaceae. 

 Several genera have a more or less widely open corolla. 

 Among these, Solanum is the genus in which the anthers 

 have attained the greatest length and the filaments are most 

 reduced. 



Comparisons in the Rubiaceac are rendered very difficult 

 by the size of the family, the inadequacy of our knowl- 

 edge of the floral structure and especially by the large 

 number of genera which show some of the characteristics 

 of the flowers of the Solanum-Cassia type ; but when all 

 characters are considered, Argostemma, Neurocalyx and 

 Strumpfia seem to be unique in this vast familv. 





i 



