1909] Oraenicher, Wisconsin Flpwers and Their Pollination. 75. 



Cirsium (Tourn.) Hill. 

 35. Cirsium altissimum (L.) Spreng. Tall Thistle. 



Blooming period from about July 29 to September 4. The- 

 entire lengtb of the purple corolla amounts to 28 mm., which is . 

 divided up among the dieli'erent parts as follows: 15 mm. for the 

 lower, very narrow portion of the tube, 6 mm. for the upper dis- 

 tended portion, and 7 mm. for the slender lobes of the corolla. 

 The outermost (peripheral) lobe of each corolla is I mm. longer 

 than the remaining 4, in other words the slit between this lobe 

 end each of its neighbors extends down to a greater distance than 

 the slits between the other lobes. Consequently insects approach- 

 ing these flowers from the outer side, as they usually do may 

 reach the bottom of the tube easier than otherwise. In this case 

 a tongue 5 mm. in length is able to drain the tube. 



Following is the list of 34 visitors : 



EUTEOPOUS. 



Bees : 1, worker s. ; 4, worker, s. and c. p. ; 6, worker, s. ; 7, male, 

 female and worker, s. and e. p.; 9, male, s. ; 13, male and female, s. ; 

 14, female, s. and e. p.; 15, female, s. ; 17, female, s. ; 20, female, s. ; 

 23, female, s. and c. p. ; 28, male, s. ; 34, female, s. and c. p. ; 54, . 

 female, s. 



HEMITEOPOUS. 



Bees: 113, female, c. p.; 114, female, e. p.; 117, female, c. p.;. 

 119, female, e. p. ; 120, female, c. p. 



Flies: 297; 313; 332— all s. or f. p. 



Butterflies: 446; 448; 450; 453; 454; 456; 464; 467; 469; 480— 



all s. 



ALLOTEOPOUS. 



Beetles : 520 ; 527— both f . v. 



Eutrop ..14 = 41.2% 



Hemitrop 18 = 52.9% 



Allotrop 2 = 5.9% 



36. Cirsium Ianceolatum (L.) Hill. Common Thistle. 



This European species has become a well known inhabitant of 

 our fields and pastures and blooms from about July 19 until the 

 end of the season, when the last flowers are destroyed by a severe 

 frost. H. Mueller 34 has studied the pollination of this species in 

 Germany. The florets agree in every respect with those of the 



34) H. Mueller, loc. cit.. p. 3S9. 



