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Darwin, Charles, 1809-1882

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


It is a curious question how bees recognise the flowers of the same
species. That the coloured corolla is the chief guide cannot be doubted.
On a fine day, when hive-bees were incessantly visiting the little blue
flowers of Lobelia erinus, I cut off all the petals of some, and only
the lower striped petals of others, and these flowers were not once
again sucked by the bees, although some actually crawled over them. The
removal of the two little upper petals alone made no difference in their
visits. Mr. J. Anderson likewise states that when he removed the
corollas of the Calceolaria, bees never visited the flowers. (11/7.
'Gardeners' Chronicle' 1853 page 534. Kurr cut off the nectaries from a
large number of flowers of several species, and found that the greater
number yielded seeds; but insects probably would not perceive the loss
of the nectary until they had inserted their proboscides into the holes
thus formed, and in doing so would fertilise the flowers. He also
removed the whole corolla from a considerable number of flowers, and
these likewise yielded seeds. Flowers which are self-fertile would
naturally produce seeds under these circumstances; but I am greatly
surprised that Delphinium consolida, as well as another species of
Delphinium, and Viola tricolor, should have produced a fair supply of
seeds when thus treated; but it does not appear that he compared the
number of the seeds thus produced with those yielded by unmutilated
flowers left to the free access of insects: 'Bedeutung der Nektarien'
1833 pages 123-135.


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