22 
BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 5, NO. 1. 
the perianth-leaves becomes more bell-shaped, and allows smaller 
bees to gain access to the pit-shaped nectaries, one of which is 
situated at the base of each of the perianth-leaves. As a rule the 
three branches of the style are about 5 mm. shorter than the six 
stamens with their anthers of 15 mm. length, and they bend out- 
ward between the latter so as to place their stigmas in the path 
of the insects that are pushing their mouth parts up towards the 
nectaries. 
When emptying their pollen the anthers begin to open at the 
base, and the slit gradually progresses downwards (in the pen- 
dulous flower) and reaches the branches of the style. At this 
juncture spontaneous self-pollination can take place in the homo- 
gamous flower, but previous to this an insect may have effected 
cross-pollination. In exceptional cases the branches of the style 
are longer and surpass the anthers entirely, and spontaneous self- 
pollination is rendered less probable. The flowers are without 
any odor. 
The principal pollinator in our region is the female bumble- 
bee Bombus arnericanoriirn Fabr., but the visits of the smaller 
bees, especially those of the genera Osmia and Andrena are un- 
doubtedly also effective. Two specimens of a Syrphid-fly ChUosia 
cyaiicsccns Loew differed in their behavior on the flowers. One of 
them inserted its proboscis from the outside between two perianth- 
leaves at their bases, and obtained nectar without rendering any 
services to the flower. This was done repeatedly. The other 
one was feeding on pollen while hanging on to the anthers, and 
probably coming in contact with the stigmas. In this manner dif- 
ferent flowers were visited whereby self-or cross-pollination may 
have been the result. The list of visitors is as follows : 
A. Hymenoptera 
Apidae: (i) Bombtts amcricanonim Fabr. female, s. and c. p.; 
(2) Osmia pumila Cr. male and female, s. ; Andrenidae : (3) 
Andrena cressonii Rob. female, s. and c. p.; (4) A. rufosignafa 
Ckli. female, s. and c. p. ; (5) Andrena sp. female, s. ; (6) 
Hahctns pro^'ancheri D. T. female, s. ; (7) H. cressonii Rob. fe- 
male, s. and c. p. ; (8) H. vcrsaUis Rob. female, s. ; (9) H. pilosus 
Sm. female, s. 
B. Diptera 
Syrphidae : ( 10) Ckilosia cyanescens Loew, s. and f . p. 
