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Darwin, Charles, 1809-1882

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

These closed
flowers have been appropriately named cleistogamic by Dr. Kuhn. (8/1.
'Botanische Zeitung' 1867 page 65.) They are remarkable from their small size
and from never opening, so that they resemble buds; their petals are rudimentary
or quite aborted; their stamens are often reduced in number, with the anthers of
very small size, containing few pollen-grains, which have remarkably thin
transparent coats, and generally emit their tubes whilst still enclosed within
the anther-cells; and, lastly, the pistil is much reduced in size, with the
stigma in some cases hardly at all developed. These flowers do not secrete
nectar or emit any odour; from their small size, as well as from the corolla
being rudimentary, they are singularly inconspicuous. Consequently insects do
not visit them; nor if they did, could they find an entrance. Such flowers are
therefore invariably self-fertilised; yet they produce an abundance of seed. In
several cases the young capsules bury themselves beneath the ground, and the
seeds are there matured. These flowers are developed before, or after, or
simultaneously with the perfect ones. Their development seems to be largely
governed by the conditions to which the plants are exposed, for during certain
seasons or in certain localities only cleistogamic or only perfect flowers are
produced.


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