This plant was discovered by Hildebrand to be heterostyled, that is, to present, like the species of Primula, a long-styled and a short-styled form, which are adapted for reciprocal fertilisation. Therefore the following comparison of the growth of the crossed and self-fertilised seedlings is not fair, for we do not know whether the difference in their heights may not be wholly due to the illegitimate fertilisation of the self-fertilised flowers.
I obtained seeds by legitimately crossing flowers on long-styled and short-styled plants, and by fertilising other flowers on both forms with pollen from the same plant. Rather more seeds were obtained by the former than by the latter process; and the legitimately crossed seeds were heavier than an equal number of the illegitimately self-fertilised seeds, in the ratio of 100 to 82. Crossed and self-fertilised seeds from the short-styled parents, after germinating on sand, were planted in pairs on the opposite sides of a large pot; and two similar lots of seeds from long-styled parents were planted in a like manner on the opposite sides of two other pots. In all three pots the legitimately crossed seedlings, when a few inches in height, were taller than the self-fertilised; and in all three pots they flowered before them by one or two days. When fully grown they were all cut down close to the ground, and as I was pressed for time, they were placed in a long row, the cut end of one plant touching the tip of another, and the total length of the legitimately crossed plants was 47 feet 7 inches, and of the illegitimately self-fertilised plants 32 feet 8 inches. Therefore the average height of the fifteen crossed plants in all three pots was 38.06 inches, and that of the fifteen self-fertilised plants 26.13 inches; or as 100 to 69.
28. CHENOPODIACEAE.—Beta vulgaris.
A single plant, no others growing in the same garden, was left to fertilise itself, and the self-fertilised seeds were collected. Seeds were also collected from a plant growing in the midst of a large bed in another garden; and as the incoherent pollen is abundant, the seeds of this plant will almost certainly have been the product of a crossed between distinct plants by means of the wind. Some of the two lots of seeds were sown on the opposite sides of two very large pots; and the young seedlings were thinned, so that an equal but considerable number was left on the two sides. These plants were thus subjected to very severe competition, as well as to poor conditions. The remaining seeds were sown out of doors in good soil in two long and not closely adjoining rows, so that these seedlings were placed under favourable conditions, and were not subjected to any mutual competition. The self-fertilised seeds in the open ground came up very badly; and on removing the soil in two or three places, it was found that many had sprouted under ground and had then died. No such case had been observed before. Owing to the large number of seedlings which thus perished, the surviving self-fertilised plants grew thinly in the row, and thus had an advantage over the crossed plants, which grew very thickly in the other row. The young plants in the two rows were protected by a little straw during the winter, and those in the two large pots were placed in the greenhouse.
There was no difference between the two lots in the pots until the ensuing spring, when they had grown a little, and then some of the crossed plants were finer and taller than any of the self-fertilised. When in full flower their stems were measured, and the measurements are given in Table 6/96.
TABLE 6/96. Beta vulgaris.
Heights of flower stems measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.