The blue calyx of the larkspur (Delphinium Ajacis); and the Napel aconite (Aconitum Napellus).
In the Aquilegia vulgaris, and in the Trollius Europæus, the calyx, by the form and colouring of its leaflets, is confounded with the second whorl so completely, that Linnæus gave it the name of corolla.
Nevertheless, in the midst of these waverings, which lead us to mistake the calicinal leaflets sometimes for bracts, sometimes for petals, we recognise perfectly the foliaceous type. Independently of its colour, which is generally green, the calyx has the same organisation as the leaf; we find in it the same tracheæ and the same stomata, the same glands and the same hairs; the veins and ramifications are also the same; and, in more than one instance, the calicinal leaflet resumes the character of a veritable leaf. Look, for example, at the five leaflets, united so strongly at the base but so free at the top, arranged in the form of a quincunx, of the hundred-leaved rose. The two external, enlarged, and lanceolate pieces are garnished on the right and left, and often at the point, with tiny foliaceous appendages, which, in every respect, imitate the composite leaf that carries the slender stem. And if we move aside the external or bearded parts of the calyx, we see that the internal bear less and less resemblance to a leaf. Thus, the part which comes next is semi-bearded; that is to say, it is furnished with foliaceous appendages only on one side; and the two upper pieces are beardless, that is, reduced to the dilated central vein.
It was these metamorphic forms of the free portion of the calicinal foliola (united below) of the rose, which originated a well-known enigma, conveyed in the following Latin distich:—
"Quique sumus fratres, unus barbatus et alter,
Imberbes duo, sum semi-berbes duo, sum semi-berbes ego."
("We are brothers, both bearded, two beardless; I am two half-bearded, and I myself am half-bearded.")
They are specially noticeable in a variety of the Rose of Bengal, in which all the petals seem to be transformed into calicinal leaves. (Fig. 44.)
The part of the calyx formed by the union of the sepals is called the tube: it is invariably the lower part. The upper portion, where the sepals are free, is the limb.
Throughout the vegetable kingdom you will not find a calyx in which the union of the sepals takes place at the top.