Euphorbia milii, the crown of thorns, Christ plant, or Christ thorn, is a species of flowering plant in the spurge family Euphorbiaceae, native to Madagascar. The species name commemorates Baron Milius, once Governor of Réunion, who introduced the species to France in 1821. It is imagined that the species was introduced to the Middle East in ancient times, and legend associates it with the crown of thorns worn by Christ. It is commonly used as an ornamental houseplant that can be grown in warmer climates. The common name is due to the thorns and deep red bracts referring to the crown thorn Jesus had to wear during his crucifixion and his blood.
It is a woody succulent subshrub or shrub growing to 1.8 m (5 ft 11 in) tall, with densely spiny stems. The straight, slender spines, up to 3 cm (1.2 in) long, help it scramble over other plants. The fleshy, green leaves are found mainly on new growth, and are up to 3.5 cm (1.4 in) long and 1.5 cm (0.59 in) broad. The flowers are small, subtended by a pair of conspicuous petal-like bracts, variably red, pink or white, up to 12 mm (0.47 in) broad. Wat Phrik in Thailand claims to be the home of the world's tallest Christ thorn plant. The plant thrives between spring and summer but produces flowers all year round.