Euphorbia rossii

Euphorbia rossii is a spiny shrub from Madagascar. It is a succulent in the spurge family, Euphorbiaceae. Sources differ on its range within the island. Kew lists the north-central part of Madagascar. LLIFLE names the Mangoky River valley in the southwest. LLIFLE places it on sand among sandstone outcrops and rock faces. The climate is dry, with rain in part of the year. Fire and harm to its habitat threaten wild plants. Taking plants for gardens may pose a further threat.

This shrub grows slowly to about 3.3 feet (1 metre) tall. Many branches rise from its base to form a dense plant. The thick main stem has a waxy coat. Thin branches reach about 1.6 feet (0.5 metres) long. Strong, curved spines crowd the stems. Smaller spines grow beside them, and young spines bear hairs. A swollen taproot shaped like a turnip stores reserves below the stems. Growers may leave this root above the soil. It can exceed 0.2 feet (0.06 metres) across. It can reach about 1 foot (0.3 metres) long.

Long, narrow leaves grow from short side shoots in summer. Their tips are round, and their stalks are very short. The plant sheds its leaves, leaving bare, spiny stems in winter. Groups of flowers form near the ends of branches. Each group may hold up to 20 small cyathia. These are the cup-like flower parts found in spurges. Parts called cyathophylls surround them. Their colour varies from plant to plant. They may be green, pale yellow, salmon or deep red. Small nectar glands range from yellow-orange to red. Small seed cases, or capsules, have lobes. They burst open and scatter their seeds.

Grow this plant in light shade. Use a mineral mix that lets water drain well. It suits pots, growth indoors, or outdoor beds in mild climates. Give modest amounts of water and feed during summer growth. It can bear some cold while at rest. Even so, cold limits its use outdoors. For safer growth, keep it above 50°F (10°C). Its branch shape and exposed root add interest in pots. The loss of leaves with the seasons brings a marked change in looks.

Growers most often use seeds to grow new plants. Cuttings can take root too. Let cut ends dry for about a week before planting. New cuts put straight into soil can rot before roots form. Harmed stems give off white latex, a poisonous sap. It can irritate skin. Keep this sap away from the eyes and mouth. Take care when handling plants due to both sap and spines.