88

DOG'S-TOOTH GRASS.

We admit that these data leave much to be desired from a chemical point of view. We may well ask, for example, how the illustrious philosopher ascertained the presence of salammoniac in nightshade? But it is not fair to criticise the science of the past, by judging it through the deceitful prism of the science of to-day. We must adopt the methods of our predecessors, when discussing natural productions from all the view-points of their applications.

DOG'S-TOOTH GRASS.

In clearing an uncultivated field we uproot a great number of herbaceous plants of different families; but those of the Gramineæ, or Grasses, invariably predominate. They are the trailing roots, or rhizomes, of certain species which have been included under the general denomination of Dog's-tooth. These tenacious and vigorous roots, so wholesome in various maladies, so injurious to cultivation,-are, whatever certain botanists may say, far from tracing their origin in all cases to the Triticum repens (couch-grass) and Panicum dactylonthose terrible enemies of the corn-field, which, once established in the soil, are with difficulty extirpated, and prove very injurious to the "golden crops." Nearly every grass which puts forth rhizomes will furnish the Dog's-tooth. We may cite, for instance, several species of Festuca (as Festuca rubra and Festuca pinnata), or fescue grass; at least two kinds of meadow grass (Poa compressa and Poa pratensis), a species of wild-oats (Avena elatior), to say nothing of the weeds Arundo phragmites and Arundo epigeios. The long rhizomes of these

RHIZOMES VERSUS ROOTS.

89

vivacious plants possess nearly the same properties, due to their saccharine principles.

How snall we distinguish these plants from one another? Their leaves have almost exactly the same configuration; they

90

THE PARTS OF THE PLANT.

are linear;* and their flowers are not apparent,—they do not attract the gaze of the passer-by. Yet they possess all the organs necessary for the reproduction of their species:-three stamens, each composed of an anther and a characteristic filament; on this anther, whose two lobes are arranged like the branches of an X, the pistil softly and tenderly balances itself on the summit of a frail thread, to which it is attached by the back. Remark, too, the two styles with feathery stigmata,† like the barbs of feathers. Nothing is wanting to constitute a complete flower.

There is even a perianth, or calyx, represented by a couple of tiny membraneous scales, scientifically known as glumellulæ ; then at the base of each spikelet, composed of one or two of these bright green lilliputian flowers, are two other and larger scales, called glumella: they represent an involucre.‡ It is almost unnecessary to add, that the free, unilocular ovary, or seed vessel, forms, as a result of its development, the seed, whose embryo adheres laterally to a farinaceous kernel, or perisperm. The union of one or more of these flowers composes a spikelet, and the union of the spikelets constitutes the spike, which may be disposed on a simple or ramified axis. Such are, in general, the characters we must keep before us in the difficult study of the Gramineæ.

* Leaves are said to be linear, when the veins do not spread out, but run from the base to the extreme point.

A stigma is the continuation of the cellular tissue of the style, and has sometimes projecting cellules of hairs.

A whorl, or ring, of bracts (floral leaves) is so called.

THE PANICUM DACTYLON.

91

Let us now see, more closely, the two plants which, according to the botanists, furnish the root of the Dog'stooth.

When walking along the sandy bank of a river, you must frequently have trodden under foot a low, almost crawling herb, remarkable for its violet-red spikes, which, three to

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ITS FAVOURITE HABITAT.

five in number, are arranged like the fingers of a hand, on the summit of a short curving stem.

This glaucous-leaved herb is the Panicum dactylon (i.e., fingered-millet) of Linnæus. The long trailing rhizomes, joined to some less prominent characters, have been sufficient for some botanists to create a special genus, Cynodon, or Kynodon (a Greek word, signifying literally "Dog's-tooth "), and to change the Linnean denomination of our grass into

FIG. 24.-(P. 93.)

Cynodon dactylon. It is seldom met with in cultivated land; but in such a locality as we have already described, and sometimes on open sandy shores, where the summer sea comes with a gentle ripple and a subdued music, it may frequently be found. Its long, tough runners creep through and over the loose soil for many yards, rooting at every joint, and furnished with flat, rather short leaves, of a glaucous hue. The flowers grow in narrow, linear spikes, arranged at the top of a short leafy stem in the form of