Euphorbia peplus (Petty Spurge or Radium Weed) is a species of Euphorbia, native to most of Europe, northern Africa, and western Asia, where it typically grows in cultivated arable land, gardens, and other disturbed land.

It should not be confused with the similarly spelled Euphorbia peplis (Purple Spurge).

It is an annual plant growing to between 5"?30 cm tall (most plants growing as weeds of cultivation tend towards the smaller end), with smooth hairless stems. The leaves are oval-acute, 1-3 cm long, with a smooth margin. It has green flowers in three-rayed umbels. The glands, typical of the Euphorbiacae, are kidney-shaped with long thin horns.

The milky latex sap is toxic, and used as a therapeutic agent for the removal of warts on the skin. Recent work also suggests that it may also be effective in treating superficial basal cell carcinomas.

Outside of its native range it is very widely naturalised and often invasive, including in Australia, New Zealand, North America, and other countries in temperate and sub-tropical regions.