Impatiens fulva.
Mr. A.W. Bennett has published an excellent description, with figures, of this
plant. (8/14. 'Journal of the Linnean Society Botany' volume 13 1872 page 147.)
He shows that the cleistogamic and perfect flowers differ in structure at a very
early period of growth, so that the existence of the former cannot be due merely
to the arrested development of the latter,--a conclusion which indeed follows
from most of the previous descriptions. Mr. Bennett found on the banks of the
Wey that the plants which bore cleistogamic flowers alone were to those bearing
perfect flowers as 20 to 1; but we should remember that this is a naturalised
species. The perfect flowers are usually barren in England; but Professor Asa
Gray writes to me that after midsummer in the United States some or many of them
produce capsules.
Impatiens noli-me-tangere.
I can add nothing of importance to Von Mohl's description, excepting that one of
the rudimentary petals shows a vestige of a nectary, as Mr. Bennett likewise
found to be the case with I. fulva. As in this latter species all five stamens
produce some pollen, though small in amount; a single anther contains, according
to Von Mohl, not more than 50 grains, and these emit their tubes while still
enclosed within it. The pollen-grains of the perfect flowers are tied together
by threads, but not, so far as I could see, those of the cleistogamic flowers;
and a provision of this kind would here have been useless, as the grains can
never be transported by insects.
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