Thinopyrum ponticum (syn. Agropyron elongatum, Elymus elongatus, Elymus obtusiflorus) is a species of grass known by the common names tall wheatgrass, rush wheatgrass, and Eurasian quackgrass. It is native to Eurasia and it has been introduced to many other parts of the world, including much of the Americas and Australia. This perennial bunchgrass can grow up to 2 meters tall. The ribbed leaves have pale green blades a few millimeters wide. The inflorescence is a spike studded with spikelets up to 3 centimeters long, each containing up to 12 flowers.