Such cases are, however, intelligible, as
almost all plants require to be occasionally intercrossed; and if any
entomiphilous species ceased to be visited by insects, it would probably
perish unless it were rendered anemophilous. A plant would be neglected
by insects if nectar failed to be secreted, unless indeed a large supply
of attractive pollen was present; and from what we have seen of the
excretion of saccharine fluid from leaves and glands being largely
governed in several cases by climatic influences, and from some few
flowers which do not now secrete nectar still retaining coloured
guiding-marks, the failure of the secretion cannot be considered as a
very improbable event. The same result would follow to a certainty, if
winged insects ceased to exist in any district, or became very rare. Now
there is only a single plant in the great order of the Cruciferae,
namely, Pringlea, which is anemophilous, and this plant is an inhabitant
of Kerguelen Land, where there are hardly any winged insects, owing
probably, as was suggested by me in the case of Madeira, to the risk
which they run of being blown out to sea and destroyed. (10/56. The
Reverend A.E. Eaton in 'Proceedings of the Royal Society' volume 23 1875
page 351.)
A remarkable fact with respect to anemophilous plants is that they are
often diclinous, that is, they are either monoecious with their sexes
separated on the same plant, or dioecious with their sexes on distinct
plants.
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