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
The above two lots of seeds were placed on damp sand, and many of the
crossed seeds germinated, as on the last occasion, before the
self-fertilised, and were rejected. Three or four pairs in the same
state of germination were planted on the opposite sides of two pots; a
single pair in a third pot; and all the remaining seeds were sown
crowded in a fourth pot. When the seedlings were about one and a half
inches in height, they were equal on both sides of the three first pots;
but in Pot 4, in which they grew crowded and were thus exposed to severe
competition, the crossed were about a third taller than the
self-fertilised. In this latter pot, when the crossed averaged 5 inches
in height, the self-fertilised were about 4 inches; nor did they look
nearly such fine plants. In all four pots the crossed plants flowered
some days before the self-fertilised. When in full flower the tallest
plant on each side was measured; but before this time the single crossed
plant in Pot 3, which was taller than its antagonist, had died and was
not measured. So that only the tallest plant on each side of three pots
was measured, as in Table 5/69.
TABLE 5/69. Lobelia ramosa (Second Generation).
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Tallest Crossed Plant in each Pot.
Column 3: Tallest Self-fertilised Plant in each Pot.
Pot 1 : 27 4/8 : 18 4/8.
Pot 2 : 21 : 19 4/8.
Pot 3 : 21 4/8 : 19.
Crowded.
Total : 70 : 57.
The average height of the three tallest crossed plants is here 23.33,
and that of the tallest self-fertilised 19 inches; or as 100 to 81.
Besides this difference in height, the crossed plants were much more
vigorous and more branched than the self-fertilised plants, and it is
unfortunate that they were not weighed.
Lobelia fulgens.
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