168 ELEMENTS OF BOTANY. 
A little search among flowers, such as those of the colum- 
bine or the foxglove, will usually disclose many which have 
had the corolla bitten through by bees, which are unable to 
get at the nectar by fair means and so steal it. 
206. Bird-Fertilized Flowers. —Some flowers with very 
long tubular corollas depend entirely upon birds to carry 
their pollen for them. Among garden flowers the gladiolus, 
the scarlet salvia and the trumpet honeysuckle are largely 
dependent upon humming-birds for their fertilization. The 
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Fic. 151. — Flower-Frequenting Bird, with a Flower. 
I, head of a sword-beak ; II, a datura flower, visited by it. (Both two- 
thirds natural size.) 
wild balsam or jewel-weed and the trumpet-creeper are also 
favorite flowers of the hoamming-bird. In Fig. 151 the head of 
a flower-visiting bird and a flower frequented by it are shown. 
207. Prevention of Self-Fertilization. — Dicecious flowers 
are of course quite incapable of self-fertilization. Pistillate 
moncecious flowers may be fertilized by staminate ones on 
the same plant, but this does not secure so good seed as is 
secured by having pollen brought to the pistil from a different 
plant. 
