THE DEHISCENCE OF ANTHERS BY APICAL PORES. 



171 



have, however, been able to supplement my descriptive 

 data very materially by a comparison of the rich materials 

 generously supplied by the directors and curators of botan- 

 ical gardens and herbaria in various parts of the world. I 

 have also been able to carry out several detailed and 

 time-consuming comparisons between the apically and the 

 longitudinally dehiscent members of the several families in 

 which dehiscence by apical pores has been described. This 

 I did to determine whether the type of floral structure 

 which is repeated with such uniformity by the apically dehis- 

 cent members of several little related families, is of frequent 

 occurrence in these families, or whether the form of the 

 anthers and the general habit characteristic of these apic- 

 ally dehiscent genera or species are aberrant in the syste- 

 matic groups to which they have been assigned by taxon- 

 omists. 



I have been able to satisfy myself more fully concerning 

 the distribution of forms by tabulating according to arbi- 

 trarily limited floristic regions the distribution of all the 

 genera of Phanerogams. The distributional phase of the 

 problem is still far from satisfactory and must necessarily 

 long remain so. These tabulations, however, confirm my 

 early impression of the greater richness of the flora of 

 some regions in species with apically dehiscent anthers. 



t 



Floral structures are to be fully interpreted only through 

 a knowledge of their ecological relations, past and present. 

 I have been able to compile a considerable series of such 

 data bearing upon the forms under consideration and while 

 these, with the few observations which I have been able to 

 make, represent only a beginning, they seem to justify 

 some very suggestive hypotheses for further investigation. 



Convinced that the great systematic differentiation 

 attained by the Apidae in South America might have a 

 significant bearing upon the problem, I have tabulated the 

 distribution of this family, and by way of comparison, that 

 of all families of the Hymenoptera. 



4 



