Couch grass (Elymus repens) is a perennial grass native to Europe, Asia, and parts of North America. It grows vigorously in open fields, prairies, hillsides, disturbed ground, and along forest edges. The plant spreads through long, creeping rhizomes that root at nodes, forming dense mats that stabilize soil and prevent erosion.

The upright stems are slender and topped with narrow, pointed leaves that are typically green and glossy. Flower spikes emerge in late spring to early summer, bearing small greenish spikelets that produce seeds for reproduction, although rhizome spread is the dominant method of propagation.

Couch grass is highly adaptable and hardy, capable of growing in a variety of soils and light conditions. Its rapid growth and resilience make it an important plant for erosion control, soil improvement, and naturalized landscaping. Medicinally, the roots have long been valued for supporting urinary and digestive health, making the plant a versatile herb in traditional folk and modern herbal medicine.