On the other hand, the smooth grains of the long-styled flowers are safely
included within the tube of the corolla, so that they cannot be blown away, but
are almost sure to adhere to the proboscis of an entering insect, which is
necessarily pressed close against the enclosed anthers.
It may be remembered that in the long-styled form of Linum perenne each separate
stigma rotates on its own axis, when the flower is mature, so as to turn its
papillose surface outwards. There can be no doubt that this movement, which is
confined to the long-styled form, is effected in order that the proper surface
of the stigma should receive pollen brought by insects from the other form. Now
with Faramea, as Fritz Muller shows, it is the stamens which rotate on their
axes in one of the two forms, namely, the short-styled, in order that their
pollen should be brushed off by insects and transported to the stigmas of the
other form. In the long-styled flowers the anthers of the short enclosed stamens
do not rotate on their axes, but dehisce on their inner sides, as is the common
rule with the Rubiaceae; and this is the best position for the adherence of the
pollen-grains to the proboscis of an entering insect. Fritz Muller therefore
infers that as the plant became heterostyled, and as the stamens of the short-
styled form increased in length, they gradually acquired the highly beneficial
power of rotating on their own axes.
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