Euphorbia peplus, commonly known as petty spurge or cancer weed, is an annual herb native to a variety of habitats including open woodlands, grasslands, and disturbed sites across Europe, northern Africa, and western Asia. It often colonizes cultivated arable land, gardens, and waste spaces. The plant typically grows 2-12 inches tall with smooth, hairless stems and oval-acute leaves arranged in a spiral. It produces inconspicuous green flowers in three-rayed umbels with distinctive kidney-shaped glands from spring to early fall. While the flowers are not showy, they are interesting upon close inspection.

Petty spurge is known for its sap, which contains ingenol mebutate, a substance toxic to rapidly replicating human tissue and traditionally used to treat skin lesions, including certain types of skin cancer. It is easy to grow and maintain, thriving in a range of soil types, from sandy to loamy, and preferring full sun to part shade. However, gardeners should handle it with care due to its toxic sap and potential to self-seed prolifically. It is important to wear gloves when handling the plant to avoid skin irritation. Petty spurge is valued for its traditional medicinal uses but is invasive in Australia, New Zealand, and North America, spreading widely in temperate and subtropical regions.CC BY-SA 4.0