The anthers of the longer stamens stand laterally farther
apart and are more nearly on the same level, for they have to brush against the
whole breadth of the insect's body. In very many other flowers the pistil, or
the stamens, or both, are rectangularly bent to one side of the flower. This
bending may be permanent, as with Lythrum and many others, or may be effected,
as in Dictamnus fraxinella and others, by a temporary movement, which occurs in
the case of the stamens when the anthers dehisce, and in the case of the pistil
when the stigma is mature; but these two movements do not always take place
simultaneously in the same flower. Now I have found no exception to the rule,
that when the stamens and pistil are bent, they bend to that side of the flower
which secretes nectar, even though there be a rudimentary nectary of large size
on the opposite side, as in some species of Corydalis. When nectar is secreted
on all sides, they bend to that side where the structure of the flower allows
the easiest access to it, as in Lythrum, various Papilionaceae, and others. The
rule consequently is, that when the pistils and stamens are curved or bent, the
stigma and anthers are thus brought into the pathway leading to the nectary.
There are a few cases which seem to be exceptions to this rule, but they are not
so in truth; for instance, in the Gloriosa lily, the stigma of the grotesque and
rectangularly bent pistil is brought, not into any pathway from the outside
towards the nectar-secreting recesses of the flower, but into the circular route
which insects follow in proceeding from one nectary to the other.
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