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Darwin, Charles, 1809-1882

"Effects of Cross and Self Fertilisation in the Vegetable Kingdom"


(11/19. 'Nature' January 8, 1874 page 189.) They thus waste much time in
searching many empty flowers, and are led to bite the holes, so as to
find out as quickly as possible whether there is any nectar present, and
if so, to obtain it.
Flowers which are partially or wholly sterile unless visited by insects
in the proper manner, such as those of most species of Salvia, of
Trifolium pratense, Phaseolus multiflorus, etc., will fail more or less
completely to produce seeds if the bees confine their visits to the
perforations. The perforated flowers of those species, which are capable
of fertilising themselves, will yield only self-fertilised seeds, and
the seedlings will in consequence be less vigorous. Therefore all plants
must suffer in some degree when bees obtain their nectar in a felonious
manner by biting holes through the corolla; and many species, it might
be thought, would thus be exterminated. But here, as is so general
throughout nature, there is a tendency towards a restored equilibrium.
If a plant suffers from being perforated, fewer individuals will be
reared, and if its nectar is highly important to the bees, these in
their turn will suffer and decrease in number; but, what is much more
effective, as soon as the plant becomes somewhat rare so as not to grow
in crowded masses, the bees will no longer be stimulated to gnaw holes
in the flowers, but will enter them in a legitimate manner.


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