I could not detect any
stamens, and in the place of the ovarium there was a little central column. The
doubleness of the perfect flowers had thus spread to the cleistogamic ones,
which therefore were rendered quite sterile.
Viola hirta.
The five stamens of the cleistogamic flowers are provided, as in the last case,
with small anthers, from all of which pollen-tubes proceed to the stigma. The
petals are not quite so much reduced as in V. canina, and the short pistil
instead of being hooked is merely bent into a rectangle. Of several perfect
flowers which I saw visited by hive-and humble-bees, six were marked, but they
produced only two capsules, some of the others having been accidentally injured.
M. Monnier was therefore mistaken in this case as in that of V. odorata, in
supposing that the perfect flowers always withered away and aborted. He states
that the peduncles of the cleistogamic flowers curve downwards and bury the
ovaries beneath the soil. (8/8. These statements are taken from Professor
Oliver's excellent article in the 'Natural History Review' July 1862 page 238.
With respect to the supposed sterility of the perfect flowers in this genus see
also Timbal-Lagrave 'Botanische Zeitung' 1854 page 772.) I may here add that
Fritz Muller, as I hear from his brother, has found in the highlands of Southern
Brazil a white-flowered species of violet which bears subterranean cleistogamic
flowers.
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