Euphorbia esula aka Leafy Spurge

Euphorbia esula, or leafy spurge, is in the spurge family. Also called wolf's milk, this perennial sheds its leaves. Its native range spans the Azores and temperate Eurasia. It grows in fields, roadsides, waste ground, and meadows. It forms dense clumps and spreads fast through roots and seeds. RHS gives a garden height of 3.3–4.9 feet (1–1.5 metres). Its short account puts stems at about 3 feet (0.9 metres). Clumps span 1.6–3.3 feet (0.5–1 metre). Growth below ground reaches much farther.

New shoots rise each spring from rhizomes, or stems below ground. Smooth, blue-green stems stand straight and branch near their tops. This plant has soft stems, though they can turn woody. Narrow, pale green leaves grow in turns along the stems. Their edges have slight waves. Leaves near flowers look more oval. All parts hold a white latex sap. Deep roots make plants hard to remove once they take hold. Roots may reach 15 feet (4.6 metres) or more below ground.

Small flowers sit within bright yellow-green bracts at stem tips. These leaf-like parts appear in late spring. The flowers then open in early summer. North Carolina State reports blooms from June into autumn. Small green seed capsules follow, each with three chambers. These ripe pods burst and throw tiny brown seeds outward. Seeds can travel 15–20 feet (4.6–6.1 metres) this way. The plant makes many seeds, which add to its root-driven spread.

Full sun suits this plant, though it also grows in part shade. It grows in clay, sand, loam, and chalk that drain well. Acid, neutral, and alkaline soils all suit it. Sources report growth in both dry and moist ground that drains well. It withstands drought and can spread fast in semi-arid sites. Its hardiness ratings are USDA zones 3–9 and RHS H6. RHS reports few pest or disease issues. Its spread is hard to control, its main garden problem.

RHS lists use in wildlife gardens but finds little value for looks. In parts of the United States, it crowds out grasses and other plants. Some states ban growing it or list it as a noxious weed. Reports list feed for sheep and goats among its uses. They also note its potential as plant matter for fuel. These uses do not make it safe for people or pets. Sources list no known uses as food or medicine. Eating any part can cause harm, including blisters in the mouth. Sap can inflame skin and cause severe eye damage. Dried plant parts can still be toxic. Wear gloves and eye protection when handling it.