FLOWERS AND INSECTS 
133 
Illustrations of this process may be taken from the flowers 
already described in connection with the prevention of 
self-pollination. 
In the flowers of the pea family,, such as the rose acacia 
(see Fig. 131), it will be 
noticed that the stamens 
and pistil are concealed 
within the keel, which 
forms the natural land- 
ing place for the bees 
which are used in pol- 
lination. This keel is 
so inserted that the 
weight of the insect de- 
presses it,, and the tip 
of the style comes in 
contact with its body. 
Not only does the 
stigma strike the body, 
but by the glancing 
blow the surface of the 
style is rubbed against 
the insect, and on this 
style, below the stigma, 
the pollen has been de- 
posited and is rubbed 
off against the insect. 
At the next flower 
visited the stigma is 
likely to strike the pol- 
len obtained from the previous flower, and the style will 
deposit a new supply of pollen. 
In the flower of the common flag (see Fig. 132) the nectar 
is deposited in a pit at the bottom of the chamber formed 
by each style and petal. In this chamber the stamen is 
found, and more or less roofing it over is the flap, or shelf, 
FIG. 138. Flower of Cypripedium, showing the 
flap overhanging the opening of the pouch, 
into which a bee is crowding its way. The 
small figure to the right shows a side view of 
the flap ; that to the left a view beneath the 
flap, showing the two dark anthers, and be- 
tween them, further down (forward), the 
stigma surface. After GIBSON. 
