THE CANADIAN ENTOMOLOGIST. 373 



THE INFLUENCE OF THE APID^ UPON THE GEOGRAPH- 

 ICAL DISTRIBUTION OF CERTAIN FLORAL TYPES. 



BY J. ARTHUR HARRIS, ST. LOUIS, MO. 

 (Continued from page 357.) 



In the three types to be considered in this place, then, the conspicu- 

 ous portion of the perianth is ^.Imost always campanulateor more generally 

 widely patent and sometimes reflexed. The anthers are regularly elongate 

 in form, linear or subulate, and basifixed on filaments of greater or lesser 

 length. The pistil is usually simple, with filiform style and punctiform 

 stigma, but to this there are rare exceptions. The Dilleniaceous type is 

 distinguished by its numerous, generally free, stamens with long or short 

 filaments, and sometimes several pistils free almost to the base. In the 

 Solanum-Cassia type the stamens are few, generally five or ten, and the 

 pistil is one, with filiform style and simple punctiform stigma. The 

 Melastomataceous type is distinguished from the Solanum-Cassia type by 

 the elongate filaments. 



In the systematic groups to which these forms have been assigned by 

 taxonomists, they are for the most part aberrant, having, for instance, a 

 patent perianth, while the type of the family may be campanulate or 

 tubular, and elongate, basifixed anthers, while the type form in the family 

 may be a short, versatile anther. This deviation from the type of the 

 group to which they systematically belong renders their structural peculi- 

 arities more conspicuous, and leads us to seek for an explanation of their 

 form in some special internal or external factor. 



The explanation of floral peculiarities is usually sought in the method 

 of their pollination, since it has been very generally assumed that flowers 

 are adaptations. The floral ecology of the forms under consideration is 

 by no means thoroughly known, but data are sufficient to be highly 

 suggestive. 



Concerning the Dilleniaceous type, the smallest of the three, no 

 general statement can be made. Some of the forms seem to be ornitho- 

 philous, some may be anemophilous, and still others appear to be adapted 

 to bees. 



There can be little doubt that the Solanum-Cassia type represents an 

 adaptation to the larger pollen-collecting bees. The class is practically 

 coextensive with Delpino's Borago type, but includes also zygomorphic 

 forms, which he treats elsewhere. Solanum and Cassia have been con- 

 clusively shown to be dependent for pollination upon the larger Apid?e, as 



November, 1905. 



