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

by Maxwell T. Masters

The fruits of Opuntia Salmiana, O. fragilis,[178] O. monacantha, and of some species of Echinocactus, have been observed to form small fruit-like branches around their summits. M. Napoléon Doumet describes the fruit as ripening as usual, but as being destitute of seeds in the interior; after a little while the fruit begins to wither, and then a circle of small buds, like those of the stem, may be seen at the top of the fruit, each bud springing from the axil of a little tuft of wool and spines found on the fruit. These little buds elongate into long shoots, produce flowers the following year, which flowers exhibit the same peculiarity. Gasparini and Tenore are said to have recorded the same fact as long since as 1832. The specimen from which the figure (fig. 93) was taken produced its fruits in the Royal Gardens at Kew, and is now preserved in the museum of that establishment. The adventitious growth in these cases appears to arise from the tufts of spines, which, it has been suggested, are the homologues of the sepals. There can, however, be little doubt that the outer and lower portion of the fruit of Opuntia and its allies is a dilatation of the flower-stalk. This is borne out by the fruits of Pereskia, which bear leaves on their surface arranged spirally; indeed, the fruits of Pereskia Bleo are mentioned as producing buds from their summits, in the same way as the Opuntia just cited. P. Bleo is said, by M. Delavaud,[179] to present this anomaly as a constant occurrence. On the summit of the primary fruit, arising apparently from the axils of the sepals, or of small leafy bracts in that situation, are a series of fruit-like branches, which, in their turn, are surmounted by others, even to the fourth generation.

The fruits of Tetragonia expansa frequently have attached to their side a secondary flower or fruit in such a position as to lead to the inference that it springs from the upper portion of the peduncle which is dilated to invest the true carpels. In other instances it is due to an adhesion of the pedicel to the side of the fruit. In either case the production of an adventitious bud might be considered as an illustration of prolification of the inflorescence, though not as was supposed by Moquin and others of axillary prolification.[180]

Buds have also been produced artificially on the surface of some of the fruits in the construction of which the axis is supposed to share; thus, the unripe fruits of some species of Lecythis were stated by Von Martius, at a meeting of the German Naturalists at Carlsruhe, to produce buds when placed in the earth. The fruit of these plants is probably of the same nature as that of the Pomaceæ, and Baillon[181] succeeded in producing buds on the surface of the inferior ovary of Jussiæa.

Some of the cases just mentioned have been considered to be instances of prolification of the fruit, but the fruit has little to do with the appearances in question.

Formation of adventitious flowers and fruits within the ovary.—This generally arises either from substitution of a flower-bud for an ovule or from prolification; there are certain cases, however, where the new growth seems not to be either due to metamorphosis or to prolification strictly.

The cut, fig. 94, represents a case where, in the dilated upper portion of the ovary of Sinapis arvensis, two flower-buds were found projecting from a raised central line, corresponding, as it would seem, to the midrib, and not to the margins of the carpel. Similar cases have occurred in Nasturtium amphibium, Brassica Rapa, and Passiflora quadrangularis.

Fig. 94.—Distended pod of Sinapis arvensis bearing in the interior stalked flower buds.

In Bromfield's 'Flora Vectensis,' p. 35, the following account is given of an abnormal development in Cardamine pratensis: "On the lower part of the corymb were several seed vessels on pedicels changed from their usual linear to an ovate elliptical figure, so as to resemble a silicula. These, on being opened, were found to contain petals of the usual colour, which in the pods above had burst from their confinement and appeared as semi-double flowers; the valves of the pod answering to the true calyx. * * * From their verticillate arrangement it is evident that these petaloid expansions were not transformed seeds, but simply a development of the common axis within the ovary into an abortive whorl of floral organs, besides which there were evident rudiments both of stamens and germens in the centre of the bundle." Baillon[182] also records a case of the same nature in Sinapis arvensis.