Vegetable Teratology / An Account of the Principal Deviations from the Usual Construction of Plants

by Maxwell T. Masters

The change which the calyx undergoes when flowers with an habitually adherent ovary become prolified, and wherein the calyx is disjoined from the ovary, has been before mentioned, but it may also be stated that, under such circumstances, the constituent sepals are frequently separated one from the other, and not rarely assume more or less of the appearance of leaves, as in proliferous flowers of Umbelliferæ, Campanulaceæ, Compositæ, &c.

As to the corolla, it was long since noticed that prolification was especially liable to occur in double flowers; indeed, Dr. Hill, who published a treatise on this subject, setting forth the method of artificially producing prolified flowers, deemed the doubling to be an almost necessary precursor of prolification;[128] but, though frequently so, it is not invariably the case that the flower so affected is double—e.g. Geum. If double, the doubling may arise from actual multiplication of the petals, or from the substitution of petals for stamens and pistils, according to the particular plant affected. Occasionally in prolified flowers the parts of the corolla, like those of the calyx, become foliaceous, and in the case of proliferous pears fleshy and succulent. There is in cultivation a kind of Cheiranthus? in which there is a constant repetition of the calyx and corolla, conjoined with an entire absence of the stamens and pistils; a short internode separates each flower from the one above it, and thus frequently ten or a dozen of these imperfect flowers may be seen on the end of a flower-stalk, giving an appearance as if they were strung like beads, at regular intervals, on a common stalk. I have seen a similar instance in a less degree in a species of Helianthemum.

The stamens are subject to various changes in prolified flowers; they assume, for instance, a leaf-like or petal-like condition, or take on them more or less of a carpellary form, or they may be entirely absent; but none of these changes seem to be at all necessarily connected with the proliferous state of the flower. Of more interest is the alteration in the position of these organs which sometimes necessarily accrues from the elongation of the axis and the disjunction of the calyx; thus, in proliferous roses the stamens become strictly hypogynous, instead of remaining perigynous. In Umbelliferæ the epigynous condition is changed for the perigynous, &c.

The condition of the pistillary organs in prolified flowers has already been alluded to. Hitherto those instances have been considered in which either the carpels were absent, or the new bud proceeded from between the carpels. There is also an interesting class of cases where the prolification is strictly intra-carpellary; the axis is so slightly prolonged that it does not protrude beyond the carpels, does not separate them in any way, but is wholly enclosed within their cavity. Doubtless, in many cases, this is merely a less perfect development of that change in which the axis protrudes beyond the carpels. This intra-carpellary prolification occurs most frequently in plants having a free central placenta, though it is not confined to them, as it is recorded among Boragineæ. A remarkable instance of this is described by Mr. H. C. Watson in the first volume of Henfrey's 'Botanical Gazette,' p. 88. In this specimen a raceme of small flowers was included within the enlarged pericarp of a species of Anchusa. But the most curious instances of this form of prolification are, no doubt, those which are met with among Primulaceæ and other orders with free central placentation.

Duchartre, in his memoir on the organogeny of plants with a free central placenta, in the 'Ann. des Sc. Nat.,' 3 sér., 1844, p. 290, among other similar instances, mentions two flowers of Cortusa Matthioli, wherein the placenta was ovuliferous at the base; but the upper portion, instead of simply elongating itself into a sterile cone, had produced a little flower with its parts slightly different from those of the normal flowers. M. Alph. de Candolle has likewise described somewhat similar deviations, and one in particular in Primula Auricula, where the elongated placenta gave off long and dilated funiculi bearing ovules, while other funiculi were destitute of these bodies, but were much dilated and foliaceous in appearance.[129] In some flowers of Rhododendron I have observed a similar condition of the ovules, which, moreover, in the primary flowers, were attached to the walls of the carpels—parietal placentation.

In speaking of these as cases of intra-carpellary prolification, it is, of course, impossible to overlook the fact that they differ in degree only from those cases where the lengthened axis projects beyond the cavity of the carpels; nevertheless they seem to demand special notice, because in these particular plants the placenta or its prolongation appears never to protrude beyond the carpels, or at least very rarely. There are, however, numerous instances of such an extension of the placenta and of prolification occurring among Primulaceæ in conjunction with the more or less complete arrest of growth of the carpels.[130] An instance of this kind has come under my own notice in a monstrosity of the chinese primrose, in which the carpels were reduced to a hardly discernible rim surrounding an umbel of five rays, each terminated by a small normally constituted flower-bud.

The ovules of a prolified flower are either unaffected, or they occur in a rudimentary form, or, lastly, they may be present in the guise of small leaves.

Under the term prolification of the fruit two or three distinct kinds of malformation appear to have been included. The term seems usually to be applied to those cases where from the centre of one fruit a branch bearing leaves, flowers, or another fruit, is seen to project, as happens occasionally in pears. Now, in many instances, not only the fruit, is repeated, but also the outer portions of the flower, which wither and fall away as the adventitious fruit ripens; so that at length the phenomenon of one fruit projecting from another is produced. It is obvious that this form of prolification in no wise differs from ordinary central prolification. Sometimes some of the whorls of the adventitious flower are suppressed; thus, M. Duchartre describes some orange blossoms as presenting alternating series of stamens and pistils one above another, while the calyces and corollas belonging to each series of stamens and pistils were entirely suppressed.[131] In other cases, doubtless, the carpellary whorl is alone repeated, the other whorls of the adventitious flower being completely absent.

Another condition, apparently sometimes mistaken for prolification of the fruit, is that in which the carpellary whorl becomes multiplied; so that there is a second or even a third series within the outer whorl of carpels. If the axis be at all prolonged, then these whorls are separated one from the other, and produce in this way an appearance of prolification. This happens frequently in oranges, as in the variety called Mellarose.[132]