[293] 'Bull. Soc. Bot. France,' 1862, vol. ix, p. 36, tab. i, and also p. 291.
[294] Ibid., 1857, vol. iv, p. 761.
CHAPTER II.
METAMORPHY OF THE FLORAL ORGANS.
One of the main arguments adduced by Goethe and others in support of the now generally received doctrine of the essential morphological identity of the various whorls of the flower is derived from the frequent appearance of one organ in the guise of another. The several parts of the flower become, as it is said, metamorphosed; sometimes the change is complete, while at other times there may be every conceivable intermediate condition between one form and another. The sense in which the terms metamorphosis, substitution, transformation, and the like, are herein used has already been explained. For the convenience of arrangement, metamorphosis of the parts of the flower may be divided into several subdivisions, according to the particular organ affected, and according to the special kind or degree of change manifested, the main subdivisions being here classed as Sepalody, Petalody, Staminody, and Pistillody.
Sepalody of the petals.—This change, spoken of by most authors as retrograde metamorphosis of the petals into sepals, or as a substitution of sepals for petals, is obviously a condition that is in most cases hardly distinguishable from virescence of the corolla, or from multiplication of the sepals. Nor is this of much consequence unless there are some special structural features which render the discrimination a matter of importance, in which case the difficulty is generally easily surmounted. The flower of the Saint-Valèry Apple may perhaps be cited under this head. In the flower in question there are neither stamens nor petals, unless the second or inner of sepals be considered as sepaloid petals (fig. 152).
Fig. 152.—Flower of St. Valèry apple, with sepaloid petals.
M. Alph. de Candolle[295] describes an instance in Primula Auricula in which the corolla had assumed the appearance of the calyx, but neither calyx nor corolla in this case possessed perfect stomata.
This malformation is much less common than the converse one of calycanthemy. Many of the recorded instances of so-called metamorphosis of the parts of the flower to sepals have occurred in monocotyledonous plants, or others in which the calyx and corolla are of the same colour, and constitute what is frequently termed the perianth; and as this is usually brightly coloured (not green) it is more convenient to group the metamorphoses in question under the general term Petalody, which thus includes all those cases in which the organs of the flower appear in the form of coloured petal-like organs, whether they be true petals or segments of a coloured perianth. As the morphological difference between the organs is one of position merely, there is little objection to be raised to this course, the less so as the term petalody merely conveys an idea of resemblance and not of absolute identity.