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Darwin, Charles, 1809-1882

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

From this fact we may
infer that most of the genera have acquired their heterostyled structure
independently of one another; that is, they have not inherited this structure
from some one or even two or three progenitors in common. It further deserves
notice that in the homostyled genera, as I am informed by Professor Asa Gray,
the stamens are either exserted or are included within the tube of the corolla,
in a nearly constant manner; so that this character, which is not even of
specific value in the heterostyled species, is often of generic value in other
members of the family.

CHAPTER IV.
HETEROSTYLED TRIMORPHIC PLANTS.
Lythrum salicaria.
Description of the three forms.
Their power and complex manner of fertilising one another.
Eighteen different unions possible.
Mid-styled form eminently feminine in nature.
Lythrum Graefferi likewise trimorphic.
L. thymifolia dimorphic.
L. Hyssopifolia homostyled.
Nesaea verticillata trimorphic.
Lagerstroemia, nature doubtful.
Oxalis, trimorphic species of.
O. Valdiviana.
O. Regnelli, the illegitimate unions quite barren.
O. speciosa.
O. sensitiva.
Homostyled species of Oxalis.
Pontederia, the one monocotyledonous genus known to include heterostyled
species.
In the previous chapters various heterostyled dimorphic plants have been
described, and now we come to heterostyled trimorphic plants, or those which
present three forms.


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