Vick’s Magazine 11: 367-368 (1888)
  DOUBLE FLOWERS

Many are the theories that have been promulgated as to the cause of the production of double flowers, but few indeed have been the practical experiments made with a view either to confirm or confute the assumptions that have been so freely made. But now we find a record in the Journal of the National Horticultural Society of France which bears so directly on the point, that we shall be doing our readers a service by calling attention to it. The record is taken from one of the reports of the German agricultural stations — institutions practically unknown here. The report in question bears the name of Dr. NOBBE — sufficient guarantee of the credit that may be assigned to the experiments.

At the outset the point is clearly raised by the inquiry as to the reason why seeds of herbaceous plants improved by cultivation show a tendency to produce double flowers? Is there any appreciable relation between the nature and condition of the seed and of the flowers which result from their development? In the horticultural department of the experimental station at Tharand an attempt has been made to find an answer to these queries. For this purpose the common Stock was selected, as completing its development in the course of one season. Twelve distinct varieties were selected from the establishment of M. E. BENARY, of Erfurt. Of each of the twelve varieties one hundred seeds, as nearly alike as possible, were chosen. These seeds were placed in Dr. NOBBE'S germinating apparatus, and submitted to a continuous and uniform temperature of 20° Cent. (equal to 68° Fahr.). After four days some of the seedlings (which must have germinated at once) were removed from the apparatus, and placed in the open ground. The other seedlings, which came up after four days and between four and nine days after the commencement of the experiment, were thrown away, so that the seedlings reserved consisted of two classes — one in which the germination had been accomplished within four days, and the other those in which germination was not appreciably commenced till after the ninth day. We need not give in detail the arrangement for the accurate comparison of the two sets of seedlings — suffice it to say that the seedlings were eventually transferred to large pots, and placed side by side, half of the pot being occupied by those of slow growth, the second half by the quickly developed seedlings. Moreover, some of the two sets of seedlings were placed in large, others in small pots; some in sterile sandy soil, care being always taken to make the experiments rigidly comparable. In all, nearly six hundred seedlings were thus under observation. In each case the time of the first appearance of the flower bud was duly noted, and the period when the first flower opened. From the large mass of statistical details so obtained the general result was arrived at that, for each variety the period of time between the sowing and the appearance of the first flower bud was long in proportion to the slowness of germination. In some cases an interval of five or six days was noticed between the seedlings of the two categories. The vigor of the plant was uniformly superior in those cases where the germination was rapid, and, moreover, when subjected to analysis the amount of dry matter as distinguished from water was always greater in the quickly than in the slowly developed plants.

But the most remarkable results are those relating to the production of double flowers. In all the varieties the proportion of double flowers was greater in the case of those that germinated quickly than in the case of the laggards. Ten plants of one variety with violet-brown flowers grown rapidly produced all double flowers, while eight plants of the same variety which had germinated slowly produced all single flowers.

The following figures convey other striking illustration of the facts now mentioned. Of one hundred plants belonging to nine different varieties the proportion of double flowers, according to the period occupied in germination, was as follows:

  Doubles Singles
After rapid germination 82.56 17.44
After slow germination 27.03 72.97

It may be suggested that the superiority might be attributable to the varying influence on the same seeds of light, heat or moisture; but the experimenters reply that the tendencies exist in the seeds themselves, for the two categories of seedlings were exposed to identically the same conditions, and yet showed the differences already mentioned. Moreover, although those seedlings which were grown on in sterile sand were much less vigorous than those grown in good soil, they, nevertheless, showed corresponding inequality as regards their flowers. Again, next to never was a single flower found in the spikes, bearing from ten to thirty double flowers, and conversely.

Lastly, hybridization shows that the seeds contain in themselves unaffected by other conditions the essence of what will be manifested in the plant later on. It must be added that there is in each variety a special tendency to produce double or single flowers as the case may be. There are some which, however treated, never yield any but single flowers, while others produce almost, or quite exclusively, double flowers, and are, in consequence, doomed to disappear.

These results are so striking that we cannot but think our great seedsmen will repeat the experiments in due season, and avail themselves of the valuable information thus placed at their disposal. That our horticultural societies will do anything so useful is, we fear, not to be hoped for. — Gardeners' Chronicle.


CybeRose note: I think it would be interesting to continue this experiment, selecting for slow or rapid germination. The doubles are sterile, which makes the selection more difficult. Even so, it might be possible to select individuals whose offspring show greater than average proportions of rapid doubles and slow singles.