Euphorbia palustris aka Marsh Spurge

Euphorbia palustris is a perennial in the spurge family. Gardeners call it marsh spurge or bog spurge. Its native range spans Europe east to Xinjiang in China. It grows in marshes and other damp places. It is introduced in Great Britain, rather than native there. This plant forms upright clumps and grows fast. Most garden plants reach 2–3 feet [0.6–0.9 metres] tall. Some reach 5 feet [1.5 metres]. Clumps spread 2–4 feet [0.6–1.2 metres] across.

Green leaves grow along the erect stems. The main leaves are oval, while branch leaves are narrower. They have smooth edges and no hairs. In autumn, the leaves turn yellow, orange, or red. The plant sheds its leaves for winter. Small green flowers form broad clusters at the stem tips. The true flowers have neither petals nor sepals. Large greenish-yellow bracts around them provide most of the colour. These bracts last longer than the small flowers. Bloom falls in late spring and early summer. Sources give May–June or June–July, depending on the garden.

Grow marsh spurge in full sun or part shade. Too much shade can make its clumps lose their shape. Some afternoon shade helps where summers are hot. It prefers moist soil but also tolerates wet ground. It can grow in shallow water. Established plants cope with some dry soil later in the season. It accepts sand, loam, clay, and poor rocky soil. Acid, neutral, and alkaline soils all suit it. Hot, humid summers may cause stress. Most sources list USDA zones 5–10; Chicago lists 4–7. The RHS gives it the cold-hardy rating H7.

Marsh spurge suits borders, bog gardens, and rain gardens. It also fits cottage gardens and woodland edges. Its bright bracts and autumn leaves give two seasons of colour. Butterflies visit the plant, while deer and rabbits tend to avoid it. It needs little upkeep and has few serious pest problems. Aphids, mealybugs, nematodes, and spider mites can still occur. Gardeners can raise it from seed, division, or stem cuttings.

Do not eat any part of this plant. Its milky sap can harm people and pets. Skin contact can cause a rash, sometimes severe. Sap in the eyes can damage the cornea. Eating plant parts can blister the lips and mouth. Wear gloves when handling it. Keep it away from children and pets.