Elymus repens (L.) Gould - Poaceae
Elymus repens subsp. repens - syn.Agropyron repens (L.) Beauv.; Elytrigia repens (L.) Desv.; Triticum repens L. - couch grass, quack grass, dog grass, quitch grass, quicken, (Gemeine) Quecke, Ackergras, Hundsgras

Perennial grass, culms 0.3-1.50 m from long rhizomes, native to Europe and Asia, naturalized elsewhere; leaves flat, soft, 5-10mm wide; rachis-joints usually flat on one side and rounded on the other; spikelets 10-18mm; glumes narrowly oblong to lanceolate, 8-14mm, sharply nerved.

„Couch grass has become naturalised throughout much of the world, and is often listed as an invasive weed. It is very difficult to remove from garden environments, as the thin rhizomes become entangled among the roots of shrubs and perennials, and each severed piece of rhizome can develop into a new plant.“ http://en.wikipedia.org/wiki/Elymus_repens

agropyrene

The rhizomes [Rhizoma Graminis] contain a small amount of essential oil, which nearly entirely consists of 1-phenyl-2,4-hexadiyne, called agropyrene (capillen) which has broad antibiotic activity. It is traditionally used as a diuretic in urinary tract infections or prevention of renal gravel.
[Structure of Agropyrene., Cymerman-Craig, J., Lack, R. A., Treibs, W., Chem. and Ind, 1959, 952]
[Das Agropyren aus dem ätherischen Öl der Queckenwurzel, ein Phenylhexadiin mit breiter antibiotischer Wirkung., Treibs, W., Parfüm. Kosm, Vol.40, 1959, 451-452]

Elymus repens (L.) Gould as Triticum repens L.
Kohl, F.G., Die officinellen Pflanzen der Pharmacopoea Germanica, t.13 (1891-1895)
http://plantgenera.org/species.php?id_species=380966