1879.] On the Fertilization of Several Species of Lobelia. 427 
ON THE FERTILIZATION OF SEVERAL SPECIES OF 
LOBELIA." 
BY WILLIAM TRELEASE. 
bod our wild flowers few are more conspicuous than the 
cardinal flower (Lobelia cardinalis), which, by its racemes of 
large, velvety red flowers, attracts many a wanderer into otherwise 
very unattractive marshes. The large blue lobelia (Z. syphilitica) 
forms also a very conspicuous feature of such places in late sum- 
mer and early autumn, while the Indian tobacco of the herb doc- 
tors (Z. inflata) is known to everybody. In addition to these, 
some twenty other species grow wild in North America, and 
lovers of flowers know well the cultivated creeping lobelia (Z. 
erinus), with its pretty blue and white flowers. To any observer 
not a botanist these are easily known as lobelias by their two- 
lipped flowers with the tube of the corolla split nearly or quite to 
its base on the upper side, while from the cleft thus formed the 
stamens project, their anthers being united to form a tube which 
is frequently bent downward at its extremity, while the style 
passes through its center. : 
To one interested in the devices by whieh nature causes cross- 
fertilization to be effected, a closer examination will reveal some 
additional facts. Nectar is so abundantly secreted, in sunshine, 
within the base of the filaments—which are there split to give 
access to it—that the basal part of the flower is often quite filled” 
with it. The structure and development of the stamens and 
pistil are essentially as Prof. Todd has described them in the Jan- 
uary number of the NATURALIST, but in addition to the shaking 
of the anthers he mentions, I think that there is sometimes 
another reason for the discharge of pollen on the back of an insect 
entering the flower. The style is in contact with the stamens only 
by its ring of collecting hairs, and a slight upward pressure on the 
tip of the anther tube would move the anthers backward without 
moving the style, and would thus imitate the action of a pump 
1 In the Ann. and Mag. of Nat. Hist., 1868, Vol. 11, p- o is a very good des- 
cription of the mode of fertilization of the “common blue Lobelia. Hildebrand 
and H. Müller, in Germany, and Delpino, in Italy, have also described the fertiliza- — 
tion of species of this genus; but as their writings are inaccessible to many American 
readers, it is thought that the following observations, made in the summer of 1878, 
at the Botanical Laboratory of Cornell University, may be of some interest. The 
insects were kindly named for me by Dr. Packard and Mr. Cresson. 
VOL, XIII.—No. VII 30 
