It is particularly in the study of the calyx that the attentive eye is struck by those proteiform movements in which nature makes sport of our absolute rules.
For example: in the Berberis vulgaris, the young calicinal leaflets have less resemblance to the bracts than to the petals of the corolla, and hence they have received the name of petaloid sepals. In other flowers this morphogenic wavering inclines towards the bracts rather than towards the corolla. We hesitate, therefore, whether we must give the name of calyx or bracts to the three under leaflets which are visible beneath the petaloid envelope of the Anemone nemorosa, or wood anemone. The calyx of the Celandine (Ranunculus ficaria), which also flowers in spring, is exactly like a whorl or involucre formed by the union of the bracts.
A similar embarrassment takes place when the calyx, in its metamorphosis, inclines too visibly in the direction of the corolla. Thus, in the Polygala vulgaris,—a little, vivacious, and very abundant plant,—the two inner leaflets of the calyx are not only larger than the three other outer leaves, but they are coloured like the petals, and become, towards the close of their flowering time, membranous, herbaceous, and marked with three strong veins: they resemble the wings of a butterfly, and have been called wings.
These peculiarities are useful in the distinction of certain species, which, at bottom, are simply varieties. Thus, in the Polygala Austriaca (Polygala amara of Keoch, Polygala uliginosa of Reichenbach),—a plant with small white or bluish leaves, which is sometimes met with on the borders of peaty swamps,—the central vein or ridge of the wings is simple, and never anastomoses with the lateral veins; while, in the Polygala vulgaris, as well as in the Polygala depressa and Polygala amarella, the vein is ramified, and anastomoses more or less widely with the laterals.
But since we are upon this subject, why should we not seize the opportunity of familiarising ourselves, under the form of a digression, with the little family of the Polygalaceæ? But no; we will adjourn the episode, since it would cut the thread of our discourse upon the calyx, our calicology.
Some calices there are, which, by their colouring, approximate so closely to the second floral envelope, that one is always tempted to call them corollas.
Such are:—The red calyx of the fuchsia;
The yellow calyx of the furze (Ulex Europæus), and of a kind of hellebore (Helleborus hyemalis);
The rosy calyx of the Christmas rose (Helleborus niger);