The Floricultural Cabinet, and Florists Magazine 92-94 (April 1856)
THE CAUSE OF DOUBLE FLOWERS
Charles Moore, Whitby Hall, Dewsbury, Yorkshire

CONVERSING with a friend, a few days back, on the most certain way to obtain the greatest quantity of double Stocks from seed, we were led to speak of the origin of double flowers in general, and that, generally speaking, the cause was little understood. The result of our conversation induced my friend to transmit me the following remarks upon the subject, which, after reading, I forward for insertion in the Cabinet, thinking, when the cause is generally understood, attention will be additionally given to it in a practical manner.

A highly concentrated state of the sap in plants induces the production of flowers, and before the petals, pistil, and stamens can be formed, it must be perfectly elaborated; thus perfected, they have a higher state of existence t nm the leaves, which are the lowest, stem and petals next, after which the pistil and stamens, and, finally, the fruit. This perfect elaboration can only be obtained by a due degree of light and height, etc.

When, however, double flowers are produced, it is generally by a change of the higher parts of the existence, of stamens and pistils into the lower state of petals; and the more the plant is checked by a poorer soil, and a sparing supply of water for a period, the more likely, by giving luxuriant food and treatment afterwards, to bring back the pistil and stamens to a grosser and lower stage of existence to petals, and thus produce double flowers. The greater the check given, the more powerful will be the effect of after luxuriance when shifted into a rich soil, placed in due heat, properly supplied with water and every requisite attention; with the greater vigour there will be a flow of crude sap, and the flower is not only then produced larger, but the crude sap as a tendency to lower the state of existence, and the stamens and pistils being higher in the scale of existence, are reduced to the more inferior condition of petals. Sometimes the scale of existence is so far reduced, that what had been originally the nucleus of a branch, but elevated by elaboration acting on the vital energy into the state of petals, stamens, and pistils, is not only reduced to petals and become double, but will shoot again into a branch, as we have had instances with Brown’s Superbe, and other Roses. The double Lychnis diurna has the stamens changed into red petals, and the pistil into green leaves, and the quantity of each greatly increased. In the Rhododendron, the flowers are produced from the terminal bud of the shoot; if the summer and autumn have been warm, the bud swells larger, and we have a branch of flowers instead of a branch of leaves the ensuing spring; but it is always diflicult to say, till the bud is evolved, whether we shall have leaves or flowers. In raising double or full flowers from seed therefore, we should carefully guide our attempts by experience; in procuring the seed, We must get it from the most double flowers we can, as the progeny always bears more or less resemblance to the parent. In the Dahlia, the flower is not, strictly speaking, full; it belongs to the compound class, in which a great number of florets are arranged on one common receptacle; in single Dahlias, and other flowers of this class, the ray or outer row of florets has the petals fully evolved and coloured; in the florets of the centre or disk, the petal is only in the state of a small tube, inside of which the stamens are situated. Rich cultivation forces these tubes to assume the state of coloured petals; sometimes tubular, as in the Qnilled Dahlias, and sometimes floculose or flattened, as in others; sometimes the stamens are changed into petals, sometimes they are abortive, but generally both these and the pistillnm are unchanged, and hence there is little difficulty in getting seed from Dahlias. Plants that are full of double flowers at one time, when the plant is vigorous, will change and come more single when checked by bad weather, or when the plant begins to ripen and get woody.

To return to the raising of seedling double flowers. Roses, Pinks, Carnations, and Ranunculus change the stamens only into petals; sometimes these are only partially so in very full flowers, and seed is comparatively easy to be obtained from them: we should, as before observed, select from the fullest and best flowers. In the Anemone, the pistils are changed into petals, the stamens unchanged; seed of these can therefore only be obtained from flowers not perfectly full, or by impregnating flowers nearly single, with a tendency only to fulness, with the anthers of full flowers. In Stocks and Wallflowers, both stamens and pistil are changed into petals; seed cannot therefore be had from full flowers in these sorts, and the only resource we have is to save seed from those in which a tendency to fulness has commenced, by having a petal or two more than usual. In growing Stocks from seed, they will be more likely to be double if the plants are checked first by a deficiency of nourishment, whether of water or manure, and afterwards excited to luxuriance by a plentiful supply; and the greater the change, the greater the likelihood of success. Old seed, or seed dried, gives a check; we have had instances of old neglected seed, which had been reckoned very inferior when the seeds were fresh and new, come almost every plant double, when a little had been left over and sold when old. The seed for raising double flowers of any sort can hardly be too old, if it will grow at all; and the weak plants, first stunted and then luxuriated, will be found most successful; the seed should be sown on heat, and the weak plants most cared for. After flowers have once been produced double or full, the habit of coming double will be retained, if kept so by rich cultivation. When any variety has begun to sport, the plants should be raised off those individuals which have not yet sported, as the sporting habit might become fixed; and this should be carefully guarded against, by propagating from those roots that show the fullest flowers. The double China Asters, Feverfew, Rockets, Daisies, etc., come double in the same way as Dahlias. The double Snapdragon is similar to the Stock, Campanula, Cistus, the Thorn, and most other double flowers, are similar to the Rose. Thus, by attention, have man of our English plants been induced to reduce double flowers, an so, no doubt, would be the result with others, both domestic and foreign, if attention were duly paid to the subject.