The plant itself has proven to be an effective molluscicide and a natural alternative to pest control. For humans it is mildly toxic and only acts as an irritant. It is very toxic to domesticated animals such as, horses, sheep, cats and dogs. The poisonous ingredients have been identified as phorbol esters. If ingested, it causes severe stomach pain, irritation of the throat and mouth, and vomiting. The sap is moderately poisonous, and causes irritation on contact with skin or eyes. The plant thrives between spring and summer but produces flowers all year round. Wat Phrik in Thailand claims to be the home of the world's tallest Christ thorn plant. 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.

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 straight, slender spines, up to 3 cm (1.2 in) long, help it scramble over other plants. It is a woody succulent subshrub or shrub growing to 1.8 m (5 ft 11 in) tall, with densely spiny stems. The common English 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 commonly used as an ornamental houseplant that can be grown in warmer climates. 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 Jesus. The native Malagasy name for this plant is songosongo also applied to several other Euphorbia species.

The species name commemorates Baron Milius, once Governor of Réunion, who introduced the species to France in 1821. Euphorbia milii, the crown of thorns, Christ plant, or Christ's thorn, is a species of flowering plant in the spurge family Euphorbiaceae, native to Madagascar.

Planta de corona de cristo