It is a herbaceous perennial plant growing to 1-1.2 m tall, with several stems branched from the base. The stems are smooth, hairless or slightly hairy. The leaves are small, lanceolate, 4-8.5 cm long and up to 1 cm broad, with a slightly wavy margin. The flowers are small, produced in umbels with a basal pair of bright yellow-green petal-like bracts. Clusters of the bracts appear in late spring, while the actual flowers do not develop until early summer. All parts of the plant contain a toxic white milky sap.
It reproduces readily by seeds that have a high germination rate and may remain viable in the soil for at least seven years. The seed capsules open explosively, dispersing seed up to 5 m from the parent plant, and may be carried further by water and wildlife. Leafy Spurge also spreads vegetatively from the root system, which is complex, reported to reach 8 m into the ground and 5 m across, and may have numerous buds.