1909] Graenieher, Wisconsin Flowers and Their Pollination. 37 



This introduced species with its purple flowers comes closest 

 to the yellow-flowered Solidago graminifolia, as the following 



figures show : 



Allotr. 



Cirsium arvense 37.2 



Solidago graminifolia 38.5 



Tube length 3y 3 mm. 



Only i introduced species, Arctium Lappa belongs here, and 

 there is no corresponding species among those studied. It com- 

 pares well with the 2 native species having a slightly longer tube 

 (4 mm.), according to the following: 



Allotr. Hemitr. Eutr. 



Native 7.8 61.1 31.1 



Introduced 6.9 63.S 29.3 



Tube length 6 mm. 



Our flora contains 1 native thistle (Cirsium altissimum), and 

 1 introduced thistle (C. lanceolatum), the florets of which are of 

 exactly the same size, and structure. A comparison of the 2 shows 



the following results : 



Allotr. Hemitr. Eutr. 



Native 5.9 52.9 41.2 



Introduced 8.3 58.4 33.3 



From a consideration of these introduced species we are led 

 to infer, that in their relations to our anthophilous insects, they 

 do not differ from our native species. The flowers of such an in- 

 troduced species receive the attention of a set of visitors cor- 

 responding to that of any of our native species presenting the same 

 floral characters. 



ROBERTSON'S FIGURES FOR SOUTHERN ILLINOIS. 



Following the comparison of the native and introduced species 

 of our region I present a table in which the figures taken from 

 Robertson's lists of visitors for Carlinville, Macoupin Co., in south- 

 ern Illinois 20 , are placed alongside of those obtained for Milwau- 

 kee. This table considers 11 species common to Milwaukee Co.. 

 Wis., and Macoupin Co.. 111. In Robertson's papers an account 

 is also given of Helianthus strumosus, and of the 3 species of 

 Bupatorium, occurring in our region, and treated in this paper, 



20) Chas. Robertson. Flowers and insects. Rosacese and Compositae 

 Trans. Acad. Sc. St. Louis, Vol. VI., No. 14, 1894. 



Chas. Robertson. Flowers and insects, loc. cit., Vol. v II., No. b, l!>9b. 



