JAN. 1907. WISCONSIN FLOM'ERS AND THEIR POLLINATION. 
31 
closing flower as that of the last named species, and consequently 
spontaneous self-pollination might not be favored to such an 
extent in B. Americaniim as in B. albidum. 
As regards pollination through the activity of insects the con- 
ditions are about the same in both species. Bees are here also the 
principal visitors. 
Besides perfect (hermaphrodite) flowers Meads (ii) has 
come across female flowers i. e., with rudimentary anthers, not 
producing any pollen. This species therefore furnishes an exam- 
ple of a gynodioecious plant. 
The following species of bees are the only visitors I have 
noted on the flowers. 
Hymenoptera 
Apidse: (i) Bombus americanorum Fabr. female, s. ; (2) 
Osmia pumila Cr. male, s. ; Andrenidse : (3) Andrena vicina Sm. 
female, c. p.; (4) Halictus 4-maculatus Rob. female, c. p. 
FAM. CONVALLARIACE.^. 
Asparagus officinalis L. Asparag^us. 
The asparagus has escaped from cultivation and is a com- 
paratively common wild plant around Milwaukee, blooming from 
about May 29 throughout the summer. Belated flowers have 
been seen even on October 6. Mueller (12) described and figured 
the greenish, pendulous and bell-shaped flowers. Breitenbach (13) 
noted the occurrence of perfect (hermaphrodite) flowers, but as 
a rule each plant has either male or female flowers only. Among 
the numerous specimens examined in our surroundings I have 
never come across one with perfect flowers. The male flower has 
a length of 6 mm., and always contains a rudimentary pistil. The 
female flower is considerably shorter (3 to 4 mm.) and is sup- 
plied with abortive anthers. 
11. M. E. Meads. Loc. cit., p. 137. 
12. H. Mueller. Befruchtung- der Blumen durch Insekten., pp. 
64-65. See also P. Knuth Handb. d. Bliietenbiologie, Vol. II., pp. 505-506. 
13. W. Breitenbach. Ueber Asparagus officinalis, etc. Bot, Ztg., 
Vol. XXXVI., pp. 163-167. 
