FLOWERS AND INSECTS 947 
the several stamens and the single carpel are in a cluster 
enclosed in-a boat-shaped structure (keel) formed by two 
of the-petals (Fig. 241). The stigma is at the summit of 
the style and projects somewhat beyond the pollen sacs, 
some of whose pollen lodges on a hairy zone on the 
style below the stigma. While the stigma is not alto- 
gether secure from receiving some pollen, the position 
does not favor it. The 
projecting keel is the nat- 
ural landing place for a 
bee visiting the flower; 
and it is so inserted that 
the weight of the insect 
depresses it, and the stig- 
ma comes in contact with 
its body. Not only does 
the stigma strike the 
body, but by the glan- 
cing blow the surface of 
the style is rubbed against 
the insect; and upon this 
style, below the stigma, 
the pollen has been shed 
and is rubbed off Beeuieh Fig. 242.—Longitudinal section of flower of 
the insect. At the next iris, showing a single stamen between the 
$28 bd drooping petal and the petal-like style; 
flower visited the stigma the stigmatic shelf is seen above the 
is likely to strike the pol- stamen, at the top of the style; the nectar 
l btained f th pit is at the junction of petal and stamen. 
en obtained Irom the pre- —Avter GRAY. 
vious flower, and the style 
will deposit a new supply of pollen. It is interesting to 
press down slightly the keel of such a flower and see the 
style apparently dart out. 
In the iris or common flag, each stamen is in a kind of 
pocket between the petal and the petal-like style; while 
the stigmatic surface is on the top of a flap or shelf which 
17 
