14 
BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 4, NOS. 1-2. 
While collecting pollen they usually do not come in contact with 
the stigma, and for this reason are not likely to bring about self- 
pollination. When proceeding from flower to flower and landing 
in the middle of a flower on the stigma their visits are apt to result 
in cross-pollination. 
SANGUINARIA CANADENSIS L. BL0ODR00T. 
Loew (i) published the results of his observations on speci- 
mens cultivated in the Botanical Garden of Berlin, and Robertson 
(2) gave an account of the pollination of this flower growing 
under natural conditions in Southern Illinois. The flowers of this 
species as observed in our surroundings agree in a general way 
with those described by Robertson. The two sepals fall off quite 
early, and the 8 or exceptionally 9 petals spread and form a 
showy white flower with a diameter ranging between 4 and 5 cm. 
These flowers often grow together in small groups and this adds 
considerably to their conspicuousness. Each flower is borne by 
a scape 12 cm. high. The two^parted stigma becomes receptive 
as soon as the flower opens, but the anthers empty their pollen 
only from the second or third day on (proterogyny) . The 
numerous stamens are directed outwardly. They differ in length, 
the outer ones being rather short while those next to the pistil 
are of sufficient length to reach the stigma. In the older flowers 
the stigma assumes a brownish color and withers. 
No nectar is produced, but insects find an ample supply of 
pollen. The larger among the visitors (bees and Syrphid-flies ) 
when alighting on the flower often come in contact with the 
stigma, Such a visit during the first 2 or 3 days results in 
cross-pollination in most instances. The flower closes towards 
the evening, and by forcing the dehiscent anthers of the inner row 
against the stigma self-pollination may be accomplished as a last 
resort if the stigma be still receptive. But in our region the 
flowers are sufficiently visited to make cross-pollination, or at 
least self pollination through insect agency the probable outcome. 
Visitors were taken as follows: 
A. BEES. 
Apidae: (1) Bombus separatus Cr. female, c. p. ; (2) Nomada 
1. Loew. Blnetenbiologiche Beitraege 1. Pringsh. Jahrb. XXII. 
1891, pp. 453-454. 
2. Chas. Robertson. Flowers and Insects, VIII. Bot. Gaz., XVII., 
1892, pp. 175-176. 
