Euphorbia lophogona aka Crown Of Thorns

Euphorbia lophogona is a succulent shrub in the spurge family. Its common names include white crown of thorns and Randramboay. It comes from Madagascar, though sources differ on its range. Kew lists the south, while LLIFLE describes the east coast. LLIFLE places it in coastal rainforest with sandy soil. Kew instead links it with desert or dry shrubland. Habitat loss, fire, and plant collecting threaten its wild populations.

This upright plant grows to about 4 feet [1.2 metres]. It may keep its leaves or lose some of them. The main stem has few branches, or none at all. It can twist as it grows and taper toward the top. Rows of thorns run along the stem. The five-sided branches widen toward their tips and show grey leaf scars. Their colour ranges from dark green to olive brown.

Glossy green leaves cluster near the tops of the stems. They are oval, with a fleshy to leathery feel. A clear central vein and white side veins mark each leaf. Leaves reach about 0.4 feet [0.12 metres] in length. They sit on short, thick leaf stalks. The flowers form on stalks with a greenish-red tint. Small yellow-green true flowers sit within larger white or pink flower-like structures. LLIFLE gives summer as the flowering season. Chicago Botanic Garden records bloom from March through October.

For growing conditions, LLIFLE favours part sun to bright shade. Chicago Botanic Garden lists full sun or partial shade. An open potting mix must let excess water drain away. LLIFLE also calls for a mix that holds some moisture. Water well, then let the mix dry somewhat before watering again. Reduce watering in winter rather than keeping the mix constantly wet. Leave space between plants so air can move through the leaves. Chicago Botanic Garden places this species in USDA zones 12–13.

Its upright shape, marked leaves, and pale flower surrounds provide ornamental interest. LLIFLE describes growing it in pots and raising new plants from cuttings. Take cuttings during active growth in spring or summer. Warmth and good airflow help them root. Let the cut ends callus for three to four weeks before potting. Keep water limited until roots form. The supplied species accounts give no details on fruit or named pests. They also provide no species-level evidence on food use or toxicity.