The crown of thorns plant, or Euphorbia splendens, is a succulent, woody, perennial shrub most often used as a decorative plant for its clusters of small flowers. As the name suggests, the stem of this plant is densely covered in thorny spikes, each up to a half-inch (1.27 cm) long. Unlike most succulents, the plant grows bright green leaves that will last for a few months before dropping off.
Crown of thorns plants continue to blossom through much of the year, often lasting from summer through fall. The plants might produce pink, white, red or yellow flowers, sprouting in clusters from new growth at the ends of branches. These flowers do not have any scent.
Specimens typically reach a height of about 3 feet (0.9 m), and plants measuring more than 6 feet (1.8 m) are not uncommon. Branches typically spread about 1 foot (.3 m). Shorter dwarf plants suitable for indoor growth are widely available as well.
Native to Madagascar, the crown of thorns plant thrives in a hot, arid climate with plenty of direct sunlight. It does not do well in cooler regions, and temperatures below 55 degrees Fahrenheit (13 degrees Celsius) will cause the plant’s leaves to fall off prematurely. Gardeners in cold areas grow these plants in containers or as houseplants.
Water also can be a problem for this plant. When over-watered, the branches of the crown of thorns plant might become spongy, and its leaves might turn yellow. For best results, proper drainage is essential, and the soil should be allowed to dry out between waterings. Less water is required when the plant is not in bloom.
The plant has common names such as Christ’s thorn or Christ’s crown, so many people assume that the crown of thorns worn by Jesus was made from the crown of thorns plant. This seems unlikely however, because the plant is not believed to have been known in the Mediterranean region at that time. Experts continue to debate the source of Jesus’ crown of thorns, with the Jerusalem thorn a likely possibility.
All portions of the crown of thorns plant are poisonous and are dangerous to humans and to many other animals. These plants should not be grown where pets, grazing animals or even small children might take a nibble. Gloves also are a good idea when handling the plant. Not only are the thorns likely to pierce unprotected skin, the plant’s sap also can cause skin irritation and inflammation similar to a poison ivy reaction.