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Darwin, Charles, 1809-1882

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

On
the supposition that we have here an hermaphrodite plant becoming dioecious,
there are two points deserving notice; firstly, the greater length of the pistil
in the incipient male form; and we have met with a nearly similar case in the
male and hermaphrodite forms of Euonymus compared with the females. Secondly,
the larger size of the pollen-grains in the more masculine flowers, which
perhaps may be attributed to their having retained their normal size; whilst
those in the incipient female flowers have been reduced. The long-styled form of
R. lanceolatus seems to correspond with the males of R. catharticus which have a
longer pistil and larger pollen-grains. Light will perhaps be thrown on the
nature of the forms in this genus, as soon as the power of both kinds of pollen
on both stigmas is ascertained. Several other species of Rhamnus are said to be
dioecious or sub-dioecious. (7/10. Lecoq 'Geogr. Bot.' tome 5 1856 pages 420-
26.) On the other hand, R. frangula is an ordinary hermaphrodite, for my son
found a large number of bushes all bearing an equal profusion of fruit.
Epigaea repens (ERICACEAE).
This plant appears to be in nearly the same state as Rhamnus catharticus. It is
described by Asa Gray as existing under four forms. (7/11. 'American Journal of
Science' July 1876. Also 'The American Naturalist' 1876 page 490.


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