The Effects of Cross & Self-Fertilisation in the Vegetable Kingdom Part 18

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 21 : 12 7/8.

Pot 1 : 14 2/8 : 16.

Pot 1 : 19 1/8 : 11 7/8.

Pot 1 : 7 : 15 2/8.

Pot 1 : 15 1/8 : 19 1/8.

Pot 2 : 20 4/8 : 12 4/8.

Pot 2 : 17 3/8 : 16 2/8.

Pot 2 : 23 7/8 : 16 2/8.

Pot 2 : 17 1/8 : 13 3/8.

Pot 2 : 20 6/8 : 13 5/8.

Pot 3 : 16 1/8 : 14 4/8.

Pot 3 : 17 6/8 : 19 4/8.

Pot 3 : 16 2/8 : 20 7/8.

Pot 3 : 10 : 7 7/8.

Pot 3 : 10 : 17 6/8.

Pot 4 : 22 1/8 : 9.

Pot 4 : 19 : 11 4/8.

Pot 4 : 18 7/8 : 11.

Pot 4 : 16 4/8 : 16.

Pot 4 : 19 2/8 : 16 3/8.

Pot 5 : 25 2/8 : 14 6/8.

Pot 5 : 22 : 16.

Pot 5 : 8 6/8 : 14 3/8.

Pot 5 : 14 2/8 : 14 2/8.

Total : 412.25 : 350.86.

The average height of the twenty-four crossed plants is here 17.17 inches, and that of the same number of self-fertilised plants 14.61; or as 100 to 85. Of the crossed plants all but five flowered, whilst several of the self-fertilised did not do so. The above pairs, whilst still in flower, but with some capsules already formed, were afterwards cut down and weighed. The crossed weighed 90.5 ounces; and an equal number of the self-fertilised only 19 ounces, or as 100 to 21; and this is an astonishing difference.

Seeds of the same two lots were also sown in two adjoining rows in the open ground. There were twenty crossed plants in the one row and thirty-two self-fertilised plants in the other row, so that the experiment was not quite fair; but not so unfair as it at first appears, for the plants in the same row were not crowded so much as seriously to interfere with each other's growth, and the ground was bare on the outside of both rows. These plants were better nourished than those in the pots and grew to a greater height. The eight tallest plants in each row were measured in the same manner as before, with the following result:--

TABLE 4/36. Reseda lutea, growing in the open ground.

Heights of plants to the summits of the flower-stems measured in inches.

Column 1: Crossed Plants.

Column 2: Self-fertilised Plants.

28 : 33 2/8.

27 3/8 : 23.

27 5/8 : 21 5/8.

28 6/8 : 20 4/8.

29 7/8 : 21 5/8.

26 6/8 : 22.

26 2/8 : 21 2/8.

30 1/8 : 21 7/8.

Total : 224.75 : 185.13

The average height of the crossed plants, whilst in full flower, was here 28.09, and that of the self-fertilised 23.14 inches; or as 100 to 82. It is a singular fact that the tallest plant in the two rows, was one of the self-fertilised. The self-fertilised plants had smaller and paler green leaves than the crossed. All the plants in the two rows were afterwards cut down and weighed. The twenty crossed plants weighed 65 ounces, and twenty self-fertilised (by calculation from the actual weight of the thirty-two self-fertilised plants) weighed 26.25 ounces; or as 100 to 40. Therefore the crossed plants did not exceed in weight the self-fertilised plants in nearly so great a degree as those growing in the pots, owing probably to the latter having been subjected to more severe mutual compet.i.tion. On the other hand, they exceeded the self-fertilised in height in a slightly greater degree.

Reseda odorata.

Plants of the common mignonette were raised from purchased seed, and several of them were placed under separate nets. Of these some became loaded with spontaneously self-fertilised capsules; others produced a few, and others not a single one. It must not be supposed that these latter plants produced no seed because their stigmas did not receive any pollen, for they were repeatedly fertilised with pollen from the same plant with no effect; but they were perfectly fertile with pollen from any other plant. Spontaneously self-fertilised seeds were saved from one of the highly self-fertile plants, and other seeds were collected from the plants growing outside the nets, which had been crossed by the bees.

These seeds after germinating on sand were planted in pairs on the opposite sides of five pots. The plants were trained up sticks, and measured to the summits of their leafy stems--the flower-stems not being included. We here have the result:--

TABLE 4/37. Reseda odorata (seedlings from a highly self-fertile plant).

Heights of plants to the summits of the leafy stems, flower-stems not included, measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 20 7/8 : 22 4/8.

Pot 1 : 34 7/8 : 28 5/8.

Pot 1 : 26 6/8 : 23 2/8.

Pot 1 : 32 6/8 : 30 4/8.

Pot 2 : 34 3/8 : 28 5/8.

Pot 2 : 34 5/8 : 30 5/8.

Pot 2 : 11 6/8 : 23.

Pot 2 : 33 3/8 : 30 1/8.

Pot 3 : 17 7/8 : 4 4/8.

Pot 3 : 27 : 25.

Pot 3 : 30 1/8 : 26 3/8.

Pot 3 : 30 2/8 : 25 1/8.

Pot 4 : 21 5/8 : 22 6/8.

Pot 4 : 28 : 25 4/8.

Pot 4 : 32 5/8 : 15 1/8.

Pot 4 : 32 3/8 : 24 6/8.

Pot 5 : 21 : 11 6/8.

Pot 5 : 25 2/8 : 19 7/8.