APRIL. 1906. SOME NOTES ON THE POLLINATION OF FLOWERS. 
J 3 
The opening of the flower begins late in the forenoon, some- 
where between n and 12 o'clock, and a short time afterwards one 
of the anthers begins to shed its pollen. One by one the extrorse 
anthers open, and on the afternoon of the first day dehiscence has 
taken place, in all of them. The flower is homogamous, the 
stigma being receptive from the start. The mode of dehiscence 
is peculiar. The outer wall of the anther represents a valve that 
at first becomes detached at the base, and gradually becomes sep- 
arated along the entire length of the anther, but remains con- 
nected at the tip. During this process the slender ribbon-shaped 
valve curls up on itself and turns its inner surface covered with 
pollen outward. Finally each anther carries such a curl covered 
with pollen at its tip. Around 4 o'clock in the afternoon the 
flower closes, the anthers are pressed up against the pistil, and 
some of the pollen is brought in contact with the stigma. In 
favorable weather the flower opens again on 2 or 3 consecutive 
days, always closing for the night or in rainy weather, and from 
the second day on the withered valves with the remnants of dry 
pollen surround the stigma. At the end of the third or fourth 
day the petals are dropped. The flower is devoid of nectar, it 
possesses a very faint sweet odor, and does not seem, according to 
my observations, to be as attractive to insects as its neighbor, the 
bloodroot. 
On the first day cross-pollination may be effected by the visits 
of insects, but if this fails to take place self-pollination is insured 
by the closing of the flower in the evening. 
The following insects have been noticed on the flowers : 
a. bE£S. * 
Apidae : ( 1 ) Ceratina dupla Say female, c. p. ; Andrenidae : (2 » 
Andrena hippotes Rob. female, c. p.; (3) Halictus coriaceus Sm. 
female, c. p.; (4) H. foxii Rob. female, c. p.; (5) H. sephyrus 
Sm. female, c. p.; (6) H. tegularis Rob. female, c. p.; (7) H. 
nearcticus Vach. female, c. p.; (8) H. anomalus Rob. female, 
c. p. ; (9) Augochlora confusa Rob. female, c. p. 
B. FLIES. 
Syrphidse : ( 10) Syrphus ribesii L., alighting on the middle of 
the flower, not f . p. 
The most regular visitors are small bees of the genus Halictus. 
* For present purposes I prefer to retain the previous classification 
of bees and divide them into Apidce (long-tongued bees), and Andren- 
idw (short-tongued bees). 
