Moquin has given an explanation of the St. Valery Apples, wherein the petals are sepaloid, the stamens absent, and where there is a double row of carpels, by supposing these peculiarities to be due to "a prolification combined with penetration and fusion of two or more flowers," but it is surely more reasonable to conceive a second row of carpels placed above the first by the prolongation of the central part of the axis. Supposing this view to be correct, the inner calyx-like whorl might be considered either as a repetition of the calycine whorl, or it might be inferred that the corolla was present in the guise of a second calyx.
Moquin-Tandon suggests another explanation—namely, that though the stamens are absent in these curious flowers, at least in their ordinary shape, they are represented by the lower row of carpels, which become, in process of development, fused with the upper or true carpels. If this were so, surely some intermediate conditions between stamen and carpel would occasionally be present; but such does not appear to be the case.[133]
In some of the instances of so-called proliferous pears the carpels would seem to be entirely absent, and the dilated portion of the axis to be alone repeated. Thus, the axis dilates to form the lower fruit without any true carpels being produced, but at its summit a whorl of leaves (sepals) is formed; above these another swelling of the axis takes place also without the formation of carpels, and this, it may be, is terminated in its turn by a branch producing leaves. In these cases there is no true prolification, but simply an extension of the axis. That the outer portion (so-called calyx-tube) of these fruits is really an axile product there can now be little doubt; and, as if to show their axile nature, they occasionally produce leaves from their sides, as before mentioned. Moquin, in the tenth volume of the 'Bulletin of the Botanical Society of France,' p. 73, says that when the case is one of prolification the lower fruit is larger and is formed of a fleshy mass; moreover, the line of demarcation between the fruits is more distinct, and there are traces of the seed-bearing cavity in the interior, and of calycine lobes at the top. On the other hand, if the case be one of hypertrophy merely, the lowermost fruit is the smallest, and there is no trace of seed-bearing cavity nor of sepals. See also under Hypertrophy.
Some other malformations usually referred to prolification of the fruit seem due to branching of the inflorescence, as in Plantago, wheat, maize; or to a simple extension of the axis beyond its ordinary limit, as in some cones of firs, &c. It is obvious that the true fruits in these cases are in no wise affected.
From these considerations it would appear better to abandon the use of the expression prolification of the fruit, as unnecessary where it is really applicable, and as delusive in the numerous other cases where it is employed.
Median prolification of one or other kind has been met with in the following genera:
Axillary prolification is the term applied to those cases wherein one or more adventitious buds spring from the axils of one or more of the parts of the flower. Engelmann makes use of the word ecblastesis to denote the same condition. Both terms are open to the objection that they do not clearly enable us to distinguish prolification occurring within the flower from a similar state originating outside the flower, within the bracts of the inflorescence. This latter condition, called by Moquin-Tandon lateral prolification (see Prolification of the Inflorescence), is as truly axillary as that to which the name is restricted. In consequence of certain peculiarities in the structure of some flowers, to be hereafter alluded to, it is not in all cases easy to decide whether the new growth springs from the interior of the flower, or from the inflorescence beneath the flower.
The accessory bud presents itself as a leaf-bud, a branch, a flower-bud, or a miniature inflorescence; it may be sessile, but is far more frequently stalked, and in more than half the number of cases it is a flower-bud or an inflorescence. There may be one or more of these buds; if two only, then they are usually placed directly opposite one to the other, on the opposite sides of the flower.
It will be seen, from the appended list, that the orders and genera in which this description of adventitious growth occurs most frequently are the following:—Cruciferæ, especially the genus Brassica; Caryophyllaceæ, e.g. Dianthus; Resedaceæ; Leguminosæ, e.g. Melilotus, Trifolium, &c.; Rosaceæ, e.g. Rosa, Potentilla, &c.; Umbelliferæ, and Campanulaceæ. For the most part, these are groups also peculiarly liable to central prolification.