Barley, wheat, and rye, grown in water cultures, were studied. The seminal roots supply the main stem with nutrients; their removal decreases the yield of grain. The nodal roots supply the tillers with nutrients; their removal decreases the yield of straw. Removal of the nodal roots stimulates the growth and activity of the seminal roots, decreasing the yield of grain but slightly. The seminal roots absorb almost twice as much water per unit of dry weight as the nodal roots.