Leafy spurge is an herbaceous perennial with thickly clustered stems growing up to 3 ft (90 cm) tall. It has deep vertical roots as well as extensive creeping lateral roots that produce adventitious buds. Leaves are alternate and narrow with smooth margins and a deep midvein. Flowers are tiny, lime-green, and enclosed by showy, yellow-green bracts. They are arranged in clusters at stem tips. Seed capsules contain three smooth, oval, mottled gray or brown seeds.