RED CLOVER. 99 
Biology of flower: If Red Clover is isolated during flowering 
time, so that no insects can visit the blooms, no seeds will be formed, 
as it depends upon insects to transport the pollen from one flower to 
another. Bumble bees, which visit the flowers in order to secure the 
nectar, are especially active in this transportation. The blossoms 
of Red Clover are peculiarly sensitive; when a bumble bee in search 
of honey forces its proboscis down and touches the lower parts of a 
flower, such a touch, if the flower is fully developed, makes the sta- 
mens and pistil protrude from the interior of the blossom into the 
open air. The bending of the stamens and pistil brings their upper 
ends into close contact with the body of the insect, which thus be- 
comes powdered with pollen from the stamens. The pistil protrudes 
a little beyond the stamens. This might seem an insignificant fact, 
but it means that the pistil has a better chance to come in contact 
with the pollen from other plants, already deposited on the body of 
the insect, than to come in contact with the pollen of its own flower. 
As the insect travels from one plant to another, carrying pollen from 
different individuals, the pistils of one are apt to be fertilized by 
pollen from another. Such cross-fertilization must, in fact, take 
place before seed can be developed. In other words, Red Clover is 
completely self-sterile. The pollen is unable to fertilize the pistils of 
the plant on which it is produced. 
As a rule, the insect carries enough pollen from different in- 
dividuals to give the pistils an opportunity to be powdered from other 
plants. There is, however, a chance that a single visit from one 
insect would be insufficient. To provide a greater opportunity for 
every flower to be fertilized, nature has made it possible to have 
each Red Clover blossom visited by insects many times. In Alfalfa 
each flower has only one chance to be fertilized (see page 115), as the 
stamens and the pistil, after the explosion of the flower, do not 
return to their original positions. A Red Clover blossom has many 
chances, as the pistil and stamens protrude for only an instant, after 
which they move back to their original positions. Their sensibility 
is not lost after the first visit of an insect; a second or third visit 
will have the same effect, and the chances of the pistil being properly 
fertilized will last as long as it remains in a condition to receive the 
pollen. 
Bumble bees are the only insects, with the exception of some 
butterflies, with a proboscis long enough to reach the nectar at the 
bottom of the flower tube. As is well known by bee-keepers, the 
ordinary honey bee is not able to gather honey from Red Clover, 
its proboscis being far too short. In spite of this, however, the ord- 
inary honey bee is of considerable importance in the fertilization of 
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