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Darwin, Charles, 1809-1882

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


Hermann Muller also has seen hive-bees flying from flower to flower of
Ranunculus bulbosus and arvensis, and of Trifolium fragiferum and
repens; and even from blue hyacinths to blue violets. (11/3. 'Bienen
Zeitung' July 1876 page 183.)
Some species of Diptera or flies keep to the flowers of the same species
with almost as much regularity as do bees; and when captured they are
found covered with pollen. I have seen Rhingia rostrata acting in this
manner with the flowers of Lychnis dioica, Ajuga reptans, and Vici
sepium. Volucella plumosa and Empis cheiroptera flew straight from
flower to flower of Myosotis sylvatica. Dolichopus nigripennis behaved
in the same manner with Potentilla tormentilla; and other Diptera with
Stellaria holostea, Helianthemum vulgare, Bellis perennis, Veronica
hederaefolia and chamoedrys; but some flies visited indifferently the
flowers of these two latter species. I have seen more than once a minute
Thrips, with pollen adhering to its body, fly from one flower to another
of the same kind; and one was observed by me crawling about within a
convolvulus with four grains of pollen adhering to its head, which were
deposited on the stigma.
Fabricius and Sprengel state that when flies have once entered the
flowers of Aristolochia they never escape,--a statement which I could
not believe, as in this case the insects would not aid in the
cross-fertilisation of the plant; and this statement has now been shown
by Hildebrand to be erroneous.


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