The Effects of Cross & Self-Fertilisation in the Vegetable KingdomDarwin, Charles
Science
The Effects of Cross & Self-Fertilisation in the Vegetable Kingdom
Darwin, Charles
Fertilization of plants; Plants -- Variation; Pollination
Firstly, in the third and fourth generations of Mimulus luteus, a tall
variety, often alluded to, having large white flowers blotched with
crimson, appeared amongst both the intercrossed and self-fertilised
plants. It prevailed in all the later self-fertilised generations to the
exclusion of every other variety, and transmitted its characters
faithfully, but disappeared from the intercrossed plants, owing no doubt
to their characters being repeatedly blended by crossing. The
self-fertilised plants belonging to this variety were not only taller,
but more fertile than the intercrossed plants; though these latter in
the earlier generations were much taller and more fertile than the
self-fertilised plants. Thus in the fifth generation the self-fertilised
plants were to the intercrossed in height as 126 to 100. In the sixth
generation they were likewise much taller and finer plants, but were not
actually measured; they produced capsules compared with those on the
intercrossed plants, in number, as 147 to 100; and the self-fertilised
capsules contained a greater number of seeds. In the seventh generation
the self-fertilised plants were to the crossed in height as 137 to 100;
and twenty flowers on these self-fertilised plants fertilised with their
own pollen yielded nineteen very fine capsules,--a degree of
self-sterility which I have not seen equalled in any other case. This
variety seems to have become specially adapted to profit in every way by
self-fertilisation, although this process was so injurious to the
parent-plants during the first four generations. It should however be
remembered that seedlings raised from this variety, when crossed by a
fresh stock, were wonderfully superior in height and fertility to the
self-fertilised plants of the corresponding generation.
Secondly, in the sixth self-fertilised generation of Ipomoea a single
plant named the Hero appeared, which exceeded by a little in height its
intercrossed opponent,--a case which had not occurred in any previous
generation. Hero transmitted the peculiar colour of its flowers, as well
as its increased tallness and a high degree of self-fertility, to its
children, grandchildren, and great-grandchildren. The self-fertilised
children of Hero were in height to other self-fertilised plants of the
same stock as 100 to 85. Ten self-fertilised capsules produced by the
grandchildren contained on an average 5.2 seeds; and this is a higher
average than was yielded in any other generation by the capsules of
self-fertilised flowers. The great-grandchildren of Hero derived from a
cross with a fresh stock were so unhealthy, from having been grown at an
unfavourable season, that their average height in comparison with that
of the self-fertilised plants cannot be judged of with any safety; but
it did not appear that they had profited even by a cross of this kind.
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