1909] Graenicher, Wisconsin Flowers <in<f Their Pollinatidn. 43 



Aster (Tonrn.) L. 

 i. Aster lateriflorus (L.) Britton.* Starved Aster. 



The flowering period of this species extends from about August 

 15 to October 9. The heads are small, 10 to 12 mm. in diameter, 

 each with about a dozen white, usually reflexed rays. In the older 

 flowers these rays become rolled up spirally. The very narrow 

 tube of the ray floret is 2 mm. long, and the style protrudes to a 

 length of 2 mm. from the mouth of the floret. All of the parts 

 of such a ray floret are white. There are from 10 to 14 disk flor- 

 ets, which are nearly white when young, but later on assume a 

 reddish-purple coloration. The lower narrow part of the disk 

 floret has a length of 2V2 mm., while the upper distended part 

 forms a cup of 1 mm. depth, and of the same width. The droplets 

 of nectar, which may be seen at the bottom of these shallow cups 

 are accessible to rather short-tongued visitors ; and the fact that 

 the lobes of the corolla, being reflexed, are out of the way of the 

 visiting insects renders access still more easy. The anther-cylin- 

 der with the style surpasses the corolla to a distance of 3 mm. At 

 first the branches of the styles are in contact with each other 

 throughout their entire length, but following the retraction of the 

 anther-cylinder these branches become .separated, remaining in 

 contact with their tips only. In the older flower a crossing of these 

 branches takes place, thereby favoring self-pollination in case 

 cross-pollination has not been effected previously. 



The following visitors* were observed on the flowers : 



EUTROPOUS. 



Bees : 13 male, s. ; 17 male, s. ; 35 male s. 



HEMITROPOUS. 



Bees : 89, female, s. and c. p.f ; 99, female, s. ; 100, female, s. ; 102, 

 male, female, s. and c. p. ; 103, female, s. ; 104, female, s. ; 105, male and 

 female, s. and c. p. ; 107, male and female, s. ; 103, male, s. ; 112, male, 

 s. ; 1 14, female, s. and c. p. ; 119. female, s. and c. p. ; 121, female, s. ; 122, 

 male and female, s. ; 128, female, s. ; 129, female, s. ; 133, female, s. ; 134, 

 female, s. ; 135. female, s. 



Wasps: 142; 147; 149; 151; 201— all s. 



Flies: 287; 298; 305; 306; 307; 313; 322; 332; 333; 342— all s., or 

 f. p. 



Butterflies and moths : 450 ; 473 ; 485 ; 493 — all s. 



* Nomenclature according to the seventh (latest) edition of Gray'3 

 Manual. 



* See the general list, n. 1 and Loew's classification p. 

 ts=sucking: c. p.=coliectlng pollen; f. p.^feeding on pollen. 



