But this does not appear to me nearly a sufficient cause,
although his plants were slightly less productive than the wild ones growing on
the Siebengbirge. My plants exhibited no tendency to become equal-styled, so as
to lose their proper long-styled character, as not rarely happens under
cultivation with several heterostyled species of Primula; but it would appear
that they had been greatly affected in function, either by long-continued
cultivation or by some other cause. We shall see in a future chapter that
heterostyled plants illegitimately fertilised during several successive
generations sometimes become more self-fertile; and this may have been the case
with my stock of the present species of Pulmonaria; but in this case we must
assume that the long-styled plants were at first sufficiently fertile to yield
some seed, instead of being absolutely self-sterile like the German plants.
Pulmonaria angustifolia.
(FIGURE 3.6. Pulmonaria angustifolia.
Left: Long-styled form.
Right: Short-styled form.)
Seedlings of this plant, raised from plants growing wild in the Isle of Wight,
were named for me by Dr. Hooker. It is so closely allied to the last species,
differing chiefly in the shape and spotting of the leaves, that the two have
been considered by several eminent botanists--for instance, Bentham--as mere
varieties.
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