Everyday Objects; Or, Picturesque Aspects of Natural History.

by W. H. Davenport Adams

Does the prunella belong to the family of Labiatæ, like the bugle?

See for yourself. The stem is quadrangular; the branches and leaves composed of two lips. The stamens are four in number, two of which are longer than the others; finally, by means of a lens, you can easily distinguish, at the very bottom of the calyx, four tiny seeds (a tetrachænium) grouped around the style. These features indicate that our plant belongs, in effect, like the bugle, to the Labiatæ family.

But mark the difference. In the bugle, as in all the species of the same genus (Ajuga), as well as in all the Teucriums—of which wild sage (Teucrium scorodonia) is the most widely-diffused type—in all the Labiatæ, the corolla is apparently unilabiate,—that is to say, the upper lip is so shortened that only the lower is prominently visible. This is not the case with our self-heal: it is distinctly bilabiate. The upper lip of the corolla here forms a positive hood, sufficiently ample to protect the didynamous stamens (two long and two short), as in Fig. 50, a; the lower lip is three-lobed, and the central lobe is largest of the three. By separating the two lips, you can see the two short stamens fixed to the base of the lower one, and the two long attached to the central part of the upper. (See Fig. 50, b.)

Let us pursue the analysis of the flowery cone you hold in your hand.

Fig. 50.—The Lips of the Prunella vulgaris.

The least practical eye is immediately struck by the arrangement of the parts and the variety of the colours. To recognise these things more thoroughly, please to cast your glances alternately from the top to the base, and from the base to the apex of its terminal flower. A little below the base you will see a pair of opposite, entire, and sinuous leaves, with shorter stalks than any of the others. The base is defined by two opposite, whitish, and nearly triangular leaves, with green points. The top of the floral spike is likewise marked by a couple of bracts; but these are much smaller, and red-coloured, like the two leaves of the calyx. The interval is occupied by bracts, which diminish in size from the base to the top of the spike; on a level with each pair six flowers are inserted, three for each bract.

The flowers, thus arranged by whorls, present some interesting peculiarities. The lower and upper show only their reddish calices; the middle, for the most part, display both a calyx and a corolla, varying from blue to pale-rose, which gives the plant a very peculiar appearance. In the under flowers, the corolla has already fallen; by separating the lips of the calyx, you may catch sight of the tetrachænium, that is, the four-seeded fruit, which is developed at the bottom of the tube. In the upper flowers, the corolla is not yet expanded. It resembles a small deep-coloured globe; you may say an eye, a bull's-eye, which, from the depths of the calyx, regards you with a piercing glance. Hence, perhaps, the French name for this plant, prunelle, an eye.

We often meet with a variety of self-heal with a white corolla, green calyx, and pinnatifid leaves, a variety of which some botanists have erroneously made a separate species, under the name of Prunella alba. It is equally wrong, in our opinion, to convert the large-flowered variety into a distinct species, by taking as its specific character the lateral cleft of the upper lip of the calyx overlapping the middle cleft; for this same characteristic is found in many individuals of the common species. The dentiform appendage which the two longest stamens exhibit at the top of their filaments is also an uncertain feature; you must have recourse to your magnifying-glass to see if this appendage is obtuse and very short, as in the large-flowered prunella, or sharp, as in the common species. As for the size of the corolla, it is, in fact, very marked; but, as a characteristic, is wholly insufficient. The creation of the varieties Pinnatifida, Laciniifolia, and Integrifolia is no better justified. For it is no rare thing to see on the same stalk, at different heights, pinnatifid, whole, and laciniate leaves.

The prunella is remarkable for the long hairs which garnish the calyx, and, principally, the edges of the bracts. Examined in the microscope, they assume the form of tiny, pointed bamboos; the knots bulge out a little, and the intervals are punctuated.