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Darwin, Charles, 1809-1882

"The Different Forms of Flowers on Plants of the Same Species"


Viola nana.
Mr. Scott sent me seeds of this Indian species from the Sikkim Terai, from which
I raised many plants, and from these other seedlings during several successive
generations. They produced an abundance of cleistogamic flowers during the whole
of each summer, but never a perfect one. When Mr. Scott wrote to me his plants
in Calcutta were behaving similarly, though his collector saw the species in
flower in its native site. This case is valuable as showing that we ought not to
infer, as has sometimes been done, that a species does not bear perfect flowers
when growing naturally, because it produces only cleistogamic flowers under
culture. The calyx of these flowers is sometimes formed of only three sepals;
two being actually suppressed and not merely coherent with the others; this
occurred with five out of thirty flowers which were examined for this purpose.
The petals are represented by extremely minute scales. Of the stamens, two bear
anthers which are in the same state as in the previous species, but, as far as I
could judge, each of the two cells contained only from 20 to 25 delicate
transparent pollen-grains. These emitted their tubes in the usual manner. The
three other stamens bore very minute rudimentary anthers, one of which was
generally larger than the other two, but none of them contained any pollen.


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