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Darwin, Charles, 1809-1882

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

) All kinds of bees and certain other insects usually visit
the flowers of the same species as long as they can, before going to
another species. This fact was observed by Aristotle with respect to the
hive-bee more than 2000 years ago, and was noticed by Dobbs in a paper
published in 1736 in the Philosophical Transactions. It may be observed
by any one, both with hive and humble-bees, in every flower-garden; not
that the habit is invariably followed. Mr. Bennett watched for several
hours many plants of Lamium album, L. purpureum, and another Labiate
plant, Nepeta glechoma, all growing mingled together on a bank near some
hives; and he found that each bee confined its visits to the same
species. (11/2. 'Nature' 1874 June 4 page 92.) The pollen of these three
plants differs in colour, so that he was able to test his observations
by examining that which adhered to the bodies of the captured bees, and
he found one kind on each bee.
Humble and hive-bees are good botanists, for they know that varieties
may differ widely in the colour of their flowers and yet belong to the
same species. I have repeatedly seen humble-bees flying straight from a
plant of the ordinary red Dictamnus fraxinella to a white variety; from
one to another very differently coloured variety of Delphinium consolida
and of Primula veris; from a dark purple to a bright yellow variety of
Viola tricolor; and with two species of Papaver, from one variety to
another which differed much in colour; but in this latter case some of
the bees flew indifferently to either species, although passing by other
genera, and thus acted as if the two species were merely varieties.


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