A plant of couch grass ( also known as twitch or quitch ),Elymus repens,syn. Agropyron repens. Couch grass is a serious invasive weed of horticulture and agriculture due to its habit of producing fast-growing rhizomes (underground stems). The rhizomes extend horizontally,giving rise at interval to new shoots and hence new plants. In gardens,the growing rhizomes often penetrate into the root area of perennial plants,making their elimination very difficult. Cultivation of couch-bearing ground results in fragmentation of the rhizomes,each piece of which can give rise to a new plant. The picture shows the base of a couch grass plant,together a tangle of roots ( below,thin ) and laterally extending rhizomes (white,thicker). The plant itself arose from the tip of a growing rhizome |