1909] Qraenicher, Wisconsin Flowers and Their Pollination. 29 



ALLOTROPOUS. 



HYMENOPTERA. 57 wasps belonging to the families Vespidae, Crabro- 

 nidse Mimesidas, Philanthid e, Nyssonidae, Larridae, Pompi- 

 lida?, Scoliida; and Mutillidse, Nos. 137—141; 156—185; 189- 

 195; 205—219.) 

 3 cuekoo-flies, Nos. 220—222. 

 28 parasitic Hymenoptera, Nos. 223 — 250. 

 2 sawnies, Nos. 251 — 252. 

 DIPTERA — 120 flies (all the flies of the list, except the hemitropous 

 Bombylids, Syrphids and Conopids considered above). 



COLEOPTERA. 34 beetles (all the beetles of the list, except the hemi- 

 tropous Meloid No. 536), Nos. 506—535, 537—540. 



HEMIPTEEA. 22 bugs, Nos. 541—562. 



Altogether 266 allotropous visitors. 



FLORAL STRUCTURE. 



INFLORESCENCE. 



In the Composite a number of florets are grouped in such a 

 manner as to present many advantages, both to the flowers as 

 regards their effective cross-pollination, as also to the insects by 

 offering them an ample and easily gathered supply of pollen and 

 nectar." These points have been discussed very thoroughly by 

 Sprengel , Delpino 10 , H. Mueller 11 , and some recent .writers. 

 Lovell 12 refers to this inflorescence as "Nature's greatest triumph 

 in flower building." 



STYLE. 



After emerging from the anther-cylinder the branches of the 

 style become divergent in most of the species under considera- 

 tion, and thereby expose the stigmatic papillae, which form a lin- 

 ing on the inner surfaces of the stylar branches, or occur along 

 the sides of the latter. Hildebrand 13 has made us acquainted 

 with the structural and mechanical peculiarities of the stylar 

 branches in quite a number of composite flowers representing dif- 

 ferent genera. In the European Eupatorium cannabinum L. these 

 parts of the flower are slender, and long, and very often come in 

 contact with those of a neighboring flower, thereby transporting 

 pollen-grains from one flower directly to the stigmatic papillae of 



9) Sprengel, loc. cit. 



10) Federico Delpino, Ulteriori osservazioni, etc., pp. 111-1^5. 



11) H. Mueller, Die Befruehtung d. Blumen, etc. pp. 378-380, (engl. edit, 

 pp. 315-318). 



12) John H. Lovell, loc. cit., p. 448. 



13) F. Hildebrand. Uetaer die Geschlechtsverhaeltnisse bei den Compo- 

 siten, 1869. 



