174 The Botanical Gazette. [June, 
on the same stem. If the stigmas are not pollinated before 
the outer anthers begin to dehisce, they might receive pollen 
main unfertilized, they may receive pollen falling from the 
anthers which now overtop them. But insects are by far the 
most important agents in effecting self-pollination, which, 
however, I think is the exception. 
The flowers remain open all day and open on two or three 
successive days. For the attention of insects the plant is in 
strong competition with a number of plants, most of which 
have the advantage, especially Claytonia Virginica, which is 
much more abundant and more attractive. f 
The flower is adapted to short-tongued bees and flies, which 
come for both honey and pollen. It seems especially attract- 
ive to bees of the genus Halictus; the list shows all of the 
early-flying species I have found in my neighborhood, except 
Hf. ligatus and confusus, and more species than I have ever 
found on any other flower. 
T have found the flowers in bloom from March 24 to May 
12. On twelve days, between March 26 and April 25, I ob- 
served the following visitors: ¥ keg 
ee : ; & 5 &e py 
pe cueeters Apidae: (1) Apis mellifica L. % Syahalo- 
nia honesta Cr. 4, s., one; (4) Ceratina tejonensis Cr. 6, 55 
9, S. ug 
_ cressonll 
Rob. 
% s. & c. p., ab.; (28) H. stultus Cr. 9, s., ¢. Pr f P bes 
H. zephyrus Sm. 2, s., ab.; (30) H. imitatus Sm. % 5» 
(31) Colletes inaequalis Say 4, s. Wd., Ss» 
iptera— Bombylidae: (32) Bombylius fratellus ) Chil- 
ab. ; Empidae : (33) Empis sp., s., one; Syrphidae: Ot 
