Euphorbia trigona, commonly known as the African Milk Tree, Cathedral Cactus, or High Chaparral, is a popular succulent plant. Despite its common names, it is not a true cactus but belongs to the Euphorbia genus, which includes plants like poinsettias. This visually striking plant is often chosen for its upright, columnar form and its reputation as an easy-to-care-for houseplant.
Understanding the Main Euphorbia Trigona Varieties
The Classic Green Form
The classic green form of Euphorbia trigona features distinct upright stems that are typically triangular in cross-section. These fleshy stems are bright green, often displaying V-shaped patterns of lighter green. Along the ridged edges of the stems, small, sharp thorns are present in pairs.
Small, teardrop-shaped leaves emerge between these thorns on each ridge. These leaves are typically short-lived, often lasting for one or two growing seasons before dropping. This variety grows into a tall, branching specimen that can resemble a candelabra.
The ‘Rubra’ or ‘Royal Red’ Form
The ‘Rubra’ or ‘Royal Red’ cultivar of Euphorbia trigona is recognized for its vibrant coloration. This form is distinguished by its stems and leaves, which take on a reddish or purplish hue. The intensity of this red coloration can vary significantly based on the amount of light the plant receives.
When exposed to bright light, the ‘Rubra’ form develops its deepest red and magenta tones. The leaves on this variety also exhibit a reddish tint, complementing the stems. New growth may initially appear greener, gradually darkening to the characteristic red as it matures and receives sufficient light.
Essential Care for Euphorbia Trigona
Euphorbia trigona thrives in bright, indirect light, though it can tolerate some direct morning or late afternoon sun. Placing it near a south or west-facing window indoors is best to ensure it receives enough light. Too much intense, direct midday sun can scorch its stems.
As a succulent, the African Milk Tree is drought-tolerant and requires careful watering to prevent root rot. Water thoroughly when the soil has completely dried out between waterings. During the plant’s dormant period in fall and winter, watering frequency should be significantly reduced.
Well-draining soil is important for the health of Euphorbia trigona. A commercial cactus or succulent mix is recommended, or a custom blend using potting soil with added sand or perlite to improve drainage. The plant prefers warm temperatures, between 65°F to 85°F (18°C to 29°C), and should be protected from temperatures below 40°F (4°C) to prevent cold damage.
Euphorbia trigona has milky white sap, which can cause skin irritation or allergic reactions upon contact. This sap is also harmful if ingested by humans or pets. Wear gloves when handling the plant to avoid contact with the sap.