Euphorbia royleana aka Sullu Spurge

Euphorbia royleana is known as Sullu spurge or Royle’s spurge. It belongs to the spurge family, Euphorbiaceae. Its native range runs from Pakistan through the Himalayas to China and Taiwan. It also grows in northern India, Nepal, and Myanmar. It inhabits dry, rocky slopes and sheltered subtropical valleys. This succulent shrub can form a small tree. Garden plants reach 6–12 feet (1.8–3.7 metres) tall. They spread 4–8 feet (1.2–2.4 metres) wide. Other accounts report trees reaching 23–26 feet (7–8 metres).

Its upright shape looks like a cactus, but it is not one. A thick trunk supports whorls of fleshy, jointed green branches. The stems have ribs and a pale, powdery coating. Short, paired spines point down along their edges. Green stems carry out most of the plant’s photosynthesis. Fleshy leaves grow near branch tips during the wet season. Each leaf has smooth edges and a narrow, spoon-like shape. Leaves soon drop, leaving bare stems in hot and cold seasons.

Small greenish-yellow cyathia appear in spring and summer. These flower-like structures form clusters of three or four near branch tips. They sit in the leaf axils on very short stalks. Leaves are often absent when the plant blooms. Smooth, reddish-brown capsules follow the flowers. The seeds are brown and have fine grooves on one side.

Give this plant full sun and soil that drains well. Light afternoon shade can also suit it. Sandy soil works outdoors; containers need a fast-draining mix. It grows at a moderate pace and needs little upkeep. Water once the soil dries several inches below the surface. Long dry spells can harm it, despite its succulent stems. Regular water helps it retain leaves, but soaked roots may rot. NC State lists USDA zones 9b–11b for outdoor growth. Growers use it as a bold accent or patio container plant. Living hedges also help keep livestock out and mark boundaries.

Pests are few, though mealybugs, spider mites, and scale may occur. Seeds and stem cuttings offer ways to raise new plants. Seed germination can be difficult. No edible uses are recorded, and eating it is unsafe. Its white latex can inflame skin and damage eyes. Swallowing plant parts can blister the lips and mouth. Wear gloves when handling it, and keep children and pets away. Traditional medicine uses the stems for asthma; this does not establish safe treatment.