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Darwin, Charles, 1809-1882

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

Of all
colours, white is the prevailing one; and of white flowers a
considerably larger proportion smell sweetly than of any other colour,
namely, 14.6 per cent; of red, only 8.2 per cent are odoriferous. (10/4.
The colours and odours of the flowers of 4200 species have been
tabulated by Landgrabe and by Schubler and Kohler. I have not seen their
original works, but a very full abstract is given in Loudon's
'Gardeners' Magazine' volume 13 1837 page 367.) The fact of a larger
proportion of white flowers smelling sweetly may depend in part on those
which are fertilised by moths requiring the double aid of
conspicuousness in the dusk and of odour. So great is the economy of
nature, that most flowers which are fertilised by crepuscular or
nocturnal insects emit their odour chiefly or exclusively in the
evening. Some flowers, however, which are highly odoriferous depend
solely on this quality for their fertilisation, such as the
night-flowering stock (Hesperis) and some species of Daphne; and these
present the rare case of flowers which are fertilised by insects being
obscurely coloured.
The storage of a supply of nectar in a protected place is manifestly
connected with the visits of insects. So is the position which the
stamens and pistils occupy, either permanently or at the proper period
through their own movements; for when mature they invariably stand in
the pathway leading to the nectary.


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