Euphorbia trigona

The African milk tree is a succulent shrub or tree and native to Angola, Congo, Gabon, Malawi, and Zaire.This species is a member of the spurge family (Euphorbiaceae) and is usually found in dry tropical forests. It is cultivated as an ornamental or houseplant. The specific epithet, trigona, means "three angled" or "triangular" and references the species three-sided stems. The common name, African milk tree, refers to its native region, and the plant's milky sap. This plant resembles a cactus and is spiny, fleshy, and evergreen. It can grow up to 6 to 12 feet tall, 5-10 feet wide, and is erect, columar, branching and has a candelabra-like habit. 

The African milk tree is a low maintenance plant. It requires partial sun when planted outdoors and bright indirect light when grown indoors. The soil should be well-drained, and sandy or loamy with a acidic to neutral pH. If used as a houseplant or potted plant, a cactus or succulent potting mix is recommended. It is best to water this plant sparingly and avoid overwatering. Water the plant when the soil feels dry at the surface depth of 1 to 2 inches. Most species prefer a warm environment between 65 to 85 degrees Fahrenheit. Outdoor plants should be brought indoors before the temperatures drops below 45 degrees Fahrenheit. Maintain good air circulation to avoid fungal diseases. This plant can be propagated by air layerings or stem cuttings.

The stems are succulent, pale to dark green, triangular, branching with ridged edges and has sharp spines. The spines are short, prickly, and measure 0.25 inches long. The spines grow in pairs along the ridges of the stems and appear maroon and then gray to yellowish-brown in color. The bark is thin, smooth, and green and will turn gray to brownish as it matures. The ridges of the stems produce small leaves that are obovate to elliptical with entire margins and are teardrop shaped. This plant rarely blooms in cultivation; however, in its native habitat the flowers are small, green or yellow and surrounded by bracts and appear during the spring and summer. The fruit is a dull red schizocarp.

Consider the African milk tree as an ornamental either indoors or outdoors. It could be used in a sunroom or office space. In warmer climates, it could be used as a hedge or in a rock garden. A container planting would make it easy to relocate the plant as the weather changes. 

Insects, Diseases, and Other Plant Problems: Monitor for mealybugs, aphids, and spider mites. Overwatering can cause root rot and other fungal diseases.

This plant is potentially invasive. It has naturalized and formed dense thickets in some warm climates such as Cuba and India.

Keep this plant out of the reach of pets and children due to its toxicity. Wear gloves when handling this plant due to the risk of skin irritation or blistering.

More information on Euphorbia.