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
Purple- and yellow-flowered illegitimate long-styled plants, LEGITIMATELY
fertilised with pollen from the common short-styled primrose :
26 : 18 : 36.4 : 60 : 9.
Or, if the two poorest capsules, including less than 15 seeds, be rejected, we
get:
26 : 16 : 41.2 : 60 : 15.
The long-styled form of the common primrose ILLEGITIMATELY fertilised with
pollen from the long-styled illegitimate purple- and yellow-flowered plants:
20 : 14 : 15.4 : 46 : 1.
Or, if the three poorest capsules be rejected, we get:
20 : 11 : 18.9 : 46 : 8.
The short-styled form of the common primrose LEGITIMATELY fertilised with pollen
from the long-styled illegitimate purple- and yellow-flowered plants:
10 : 6 : 30.5 : 61 : 6.
If we compare the figures in this table with those given in the first chapter,
showing the normal fertility of the common primrose, we shall see that the
illegitimate purple- and yellow-flowered varieties are very sterile. For
instance, 72 flowers were fertilised with their own pollen and produced only 11
good capsules; but by the standard they ought to have produced 48 capsules; and
each of these ought to have contained on an average 52.2 seeds, instead of only
11.5 seeds. When these plants were illegitimately and legitimately fertilised
with pollen from the common primrose, the average numbers were increased, but
were far from attaining the normal standards. So it was when both forms of the
common primrose were fertilised with pollen from these illegitimate plants; and
this shows that their male as well as their female organs were in a deteriorated
condition. The sterility of these plants was shown in another way, namely, by
their not producing any capsules when the access of all insects (except such
minute ones as Thrips) was prevented; for under these circumstances the common
long-styled primrose produces a considerable number of capsules. There can,
therefore, be no doubt that the fertility of these plants was greatly impaired.
The loss is not correlated with the colour of the flower; and it was to
ascertain this point that I made so many experiments. As the parent-plant
growing in Edinburgh was found by Mr. Scott to be in a high degree sterile, it
may have transmitted a similar tendency to its offspring, independently of their
illegitimate birth. I am, however, inclined to attribute some weight to the
illegitimacy of their descent, both from the analogy of other cases, and more
especially from the fact that when the plants were LEGITIMATELY fertilised with
pollen of the common primrose they yielded an average, as may be seen in the
table, of only 5 more seeds than when ILLEGITIMATELY fertilised with the same
pollen. Now we know that it is eminently characteristic of the illegitimate
offspring of Primula Sinensis that they yield but few more seeds when
legitimately fertilised than when fertilised with their own-form pollen.
Primula veris, Brit. Fl.
Var. officinalis of Linn., P. officinalis OF Jacq.
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