The Different Forms of Flowers on Plants of the Same SpeciesDarwin, Charles
Science
The Different Forms of Flowers on Plants of the Same Species
Darwin, Charles
Fertilization of plants; Heterostylism; Plant physiology; Plants -- Variation; Pollination
This short-styled plant was fertilised in the same manner and at the same time
with the last; and ten capsules yielded an average of 113.9, with a maximum of
137 and a minimum of 90. Hence this plant produced no less than 137 per cent of
seeds in comparison with the normal standard.]
CONCLUDING REMARKS ON THE ILLEGITIMATE OFFSPRING OF THE THREE FORMS OF Lythrum
salicaria.
From the three forms occurring in approximately equal numbers in a state of
nature, and from the results of sowing seed naturally produced, there is reason
to believe that each form, when legitimately fertilised, reproduces all three
forms in about equal numbers. Now, we have seen (and the fact is a very singular
one) that the fifty-six plants produced from the long-styled form,
illegitimately fertilised with pollen from the same form (Class 1 and 2), were
all long-styled. The short-styled form, when self-fertilised (Class 3), produced
eight short-styled and one long-styled plant; and the mid-styled form, similarly
treated (Class 4), produced three mid-styled and one long-styled offspring; so
that these two forms, when illegitimately fertilised with pollen from the same
form, evince a strong, but not exclusive, tendency to reproduce the parent-form.
When the short-styled form was illegitimately fertilised by the long-styled form
(Class 5), and again when the mid-styled was illegitimately fertilised by the
long-styled (Class 6), in each case the two parent-forms alone were reproduced.
As thirty-seven plants were raised from these two unions, we may, with much
confidence, believe that it is the rule that plants thus derived usually consist
of both parent-forms, but not of the third form. When, however, the mid-styled
form was illegitimately fertilised by the longest stamens of the short-styled
(Class 7), the same rule did not hold good; for the seedlings consisted of all
three forms. The illegitimate union from which these latter seedlings were
raised is, as previously stated, singularly fertile, and the seedlings
themselves exhibited no signs of sterility and grew to their full height. From
the consideration of these several facts, and from analogous ones to be given
under Oxalis, it seems probable that in a state of nature the pistil of each
form usually receives, through the agency of insects, pollen from the stamens of
corresponding height from both the other forms. But the case last given shows
that the application of two kinds of pollen is not indispensable for the
production of all three forms. Hildebrand has suggested that the cause of all
three forms being regularly and naturally reproduced, may be that some of the
flowers are fertilised with one kind of pollen, and others on the same plant
with the other kind of pollen. Finally, of the three forms, the long-styled
evinces somewhat the strongest tendency to reappear amongst the offspring,
whether both, or one, or neither of the parents are long-styled.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account