Botanical Origin—Agropyrum repens P. Beauv. (Triticum repens L.), a widely diffused weed, growing in fields and waste places in all parts of Europe, in Northern Asia down to the region south of the Caspian, also in North America; and in South America to Patagonia and Tierra del Fuego.

History—The ancients were familiar with a grass termed [Greek Agrôstis] and Gramen, having a creeping rootstock like that under notice. It is impossible to determine to what species the plant is referable, though it is probable that the grass Cynodon Dactylon Pers., as well as Agropyrum repens, was included under these names.

Dioscorides asserts that its root taken in the form of decoction, is a useful remedy in suppression of urine and vesical calculus. The same statements are made by Pliny; and again occur in the writings of Oribasius[2717] and Marcellus Empiricus[2718] in the 4th, and of Aëtius[2719] in the 6th century, and are repeated in the mediæval herbals,[2720] where also figures of the plant may be found, as for instance in Dodonæus. The drug is also met with in the German pharmaceutical tariffs of the 16th century. Turner[2721] and Gerarde both ascribe to a decoction of grass root diuretic and lithontriptic virtues. The drug is still a domestic remedy in great repute in France, being taken as a demulcent and sudorific in the form of tisane.

Description—Couch-grass has a long, stiff, pale yellow, smooth rhizome, ⅒ of an inch in diameter, creeping close under the surface of the ground, occasionally branching, marked at intervals of about an inch by nodes, which bear slender branching roots and the remains of sheathing rudimentary leaves.

As found in the shops, the rhizome is always free from rootlets, cut into short lengths of ⅛ to ¼ of an inch, and dried. It is thus in the form of little, shining, straw-coloured, many-edged, tubular pieces, which are without odour, but have a slightly sweet taste.

Microscopic Structure—A transverse section of this rhizome shows two different portions of tissue, separated by the so-called nucleus-sheath. The latter consists of an unbroken ring of prismatic cells, analogous to those occurring in sarsaparilla. In Rhizoma Graminis, the outer part of the tissue exhibits a diffuse circle of about 20 liber bundles, and the interior part about the same number of fibro-vascular bundles more densely packed. The pith is reduced to a few rows of cells, the rhizome being always hollow, except at the nodes. No solid contents are to be met with in the tissue.

Chemical Composition—The constituents of couch-grass include no substance to which medicinal powers can be ascribed. The juice of the rhizome afforded to H. Müller[2722] about 3 per cent. of sugar, and 7 to 8 per cent. of Triticin, C₁₂H₂₂O₁₁, a tasteless, amorphous, gummy substance, easily transformed into sugar if its concentrated solution is kept for a short time at 110°C. When treated with nitric acid, it yields oxalic acid. The rhizome affords also another gummy matter containing nitrogen, and quickly undergoing decomposition; the drug moreover is somewhat rich in acid malates. Mannite is probably occasionally present as in taraxacum (p. 394), for such is the inference we draw from the opposite results obtained by Stenhouse and by Völcker. Starch, pectin and resin are wanting. The rhizome leaves 4½ per cent. of ash.

Uses—A decoction of the rhizome has of late been recommended in mucous discharge from the bladder.

Substitutes—Agropyrum acutum R. et S., A. pungens R. et S., and A. junceum P. Beauv., by some botanists regarded as mere maritime varieties of A. repens, have rootstocks perfectly similar to this latter.

Cynodon Dactylon Pers., a grass very common in the South of Europe and the warmer parts of Western Europe, also indigenous to Northern Africa as far as Sennaar and Abyssinia, affords the Gros Chiendent or Chiendent pied-de-poule of the French. It is a rhizome differing from that of couch-grass in being a little stouter. Under the microscope it displays an entirely different structure, inasmuch as it contains a large number of much stronger fibro-vascular bundles, and a cellular tissue loaded with starch, and is therefore in appearance much more woody. It thus approximates to the rhizome of Carex arenaria L., which is as much used in Germany as that of Cynodon in Southern Europe. The latter appears to contain Asparagin (the Cynodin of Semmola[2723]), or a substance similar to it.