Plants belonging to this class commonly
bear both kinds of flowers every season, and the perfect flowers of
Viola canina yield fine capsules, but only when visited by bees. We have
also seen that the seedlings of Ononis minutissima, raised from the
perfect flowers fertilised with pollen from another plant, were finer
than those from self-fertilised flowers; and this was likewise the case
to a certain extent with Vandellia. As therefore no species which at one
time bore small and inconspicuous flowers has had all its flowers
rendered cleistogene, I must believe that plants now bearing small and
inconspicuous flowers profit by their still remaining open, so as to be
occasionally intercrossed by insects. It has been one of the greatest
oversights in my work that I did not experimentise on such flowers,
owing to the difficulty of fertilising them, and to my not having seen
the importance of the subject. (10/28. Some of the species of Solanum
would be good ones for such experiments, for they are said by Hermann
Muller 'Befruchtung' page 434, to be unattractive to insects from not
secreting nectar, not producing much pollen, and not being very
conspicuous. Hence probably it is that, according to Verlot 'Production
des Varieties' 1865 page 72, the varieties of "les aubergines et les
tomates" (species of Solanum) do not intercross when they are cultivated
near together; but it should be remembered that these are not endemic
species.
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