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
In a future chapter, when I treat of the offspring from heterostyled dimorphic
and trimorphic plants illegitimately fertilised with their own-form pollen, I
shall have occasion to show that with the present species and several others,
equal-styled varieties sometimes appear.
Primula elatior, Jacq.
Bardfield oxlip of English authors.
This plant, as well as the last or cowslip (P. veris, vel officinalis), and the
primrose (P. vulgaris, vel acaulis) have been considered by some botanists as
varieties of the same species. But they are all three undoubtedly distinct, as
will be shown in the next chapter. The present species resembles to a certain
extent in general appearance the common oxlip, which is a hybrid between the
cowslip and primrose. Primula elatior is found in England only in two or three
of the eastern counties; and I was supplied with living plants by Mr. Doubleday,
who, as I believe, first called attention to its existence in England. It is
common in some parts of the Continent; and H. Muller has seen several kinds of
humble-bees and other bees, and Bombylius, visiting the flowers in North
Germany. (1/9. ‘Die Befruchtung der Blumen’ page 347.)
The results of my trials on the relative fertility of the two forms, when
legitimately and illegitimately fertilised, are given in Table 1.8.
TABLE 1.8. Primula elatior.
Column 1: Nature of the Union.
Column 2: Number of Flowers fertilised.
Column 3: Number of good Capsules produced.
Column 4: Maximum Number of Seeds in any one Capsule.
Column 5: Minimum Number of Seeds in any one Capsule.
Column 6: Average Number of Seeds per Capsule.
Long-styled by pollen of short-styled. Legitimate union :
10 : 6 : 62 : 34 : 46.5.
Long-styled by own-form pollen. Illegitimate union :
20 : 4 : 49* : 2 : 27.7.
(*These seeds were so poor and small that they could hardly have germinated.)
Short-styled by pollen of long-styled. Legitimate union:
10 : 8 : 61 : 37 : 47.7.
Short-styled by own-form pollen. Illegitimate union :
17 : 3 : 19 : 9 : 12.1.
SUMMARY:
The two legitimate unions together :
20 : 14 : 62 : 37 : 47.1.
The two illegitimate unions together :
37 : 7 : 49* : 2 : 35.5.
(*These seeds were so poor and small that they could hardly have germinated.)
Public-domain text, read in full here on John Shaqi.
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