The ordinary or perfect flowers have been said by some authors never to produce
capsules; but this is an error, though only a small proportion of them do so.
This appears to depend in some cases on their anthers not containing even a
trace of pollen, but more generally on bees not visiting the flowers. I twice
covered with a net a group of flowers, and marked with threads twelve of them
which had not as yet expanded. This precaution is necessary, for though as a
general rule the perfect flowers appear considerably before the cleistogamic
ones, yet occasionally some of the latter are produced early in the season, and
their capsules might readily be mistaken for those produced by the perfect
flowers. Not one of the twelve marked perfect flowers yielded a capsule, whilst
others under the net which had been artificially fertilised produced five
capsules; and these contained exactly the same average number of seeds as some
capsules from flowers outside the net which had been fertilised by bees. I have
repeatedly seen Bombus hortorum, lapidarius, and a third species, as well as
hive-bees, sucking the flowers of this violet: I marked six which were thus
visited, and four of them produced fine capsules; the two others were gnawed off
by some animal. I watched Bombus hortorum for some time, and whenever it came to
a flower which did not stand in a convenient position to be sucked, it bit a
hole through the spur-like nectary.
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