'Die Schutzmittel der Bluthen gegen
unberufene Gaste' 1876 page 25.), the deficiency of the glands in the
cleistogamic flowers of these plants may perhaps be accounted for by their not
requiring any such protection.
As the Asclepiadous genus Stapelia is said to produce cleistogamic flowers, the
following case may be worth giving. I have never heard of the perfect flowers of
Hoya carnosa setting seeds in this country, but some capsules were produced in
Mr. Farrer's hothouse; and the gardener detected that they were the product of
minute bud-like bodies, three or four of which could sometimes be found on the
same umbel with the perfect flowers. They were quite closed and hardly thicker
than their peduncles. The sepals presented nothing particular, but internally
and alternating with them, there were five small flattened heart-shaped
papillae, like rudiments of petals; but the homological nature of which appeared
doubtful to Mr. Bentham and Dr. Hooker. No trace of anthers or of stamens could
be detected; and I knew from having examined many cleistogamic flowers what to
look for. There were two ovaries, full of ovules, quite open at their upper
ends, with their edges festooned, but with no trace of a proper stigma. In all
these flowers one of the two ovaries withered and blackened long before the
other. The one perfect capsule, 3 1/2 inches in length, which was sent me, had
likewise been developed from a single carpel.
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