Euphorbia avasmontana aka Slender Candelabra Euphorbia

Euphorbia avasmontana is a spiny succulent in the spurge family. Its common names include slender candelabra euphorbia and crown of thorns. Its native range runs from Namibia into South Africa’s Northern Cape. It grows in deserts and dry shrubland. Plants occur around the Orange River, in Namaqualand and Bushmanland. They often grow on slopes, sometimes beside Aloe dichotoma. Their habitats receive about 150–300 mm of rain each year.

This shrub forms a clump of upright, cactus-like stems. Branches rise from the base, with few branches higher up. It reaches about 6.6–8.2 feet [2–2.5 metres] tall. Suckers can build a clump almost as wide as tall. Each stem measures about 0.20–0.23 feet [0.06–0.07 metres] across. The stems narrow at uneven points along their length. They contain a white, milky latex. Five to seven ribs run along each stem, with shallow grooves between them. Leaves appear on young growth during much of the year.

Straight spines grow in pairs along the stem ribs. A hard, narrow strip joins them along each ridge. The spines reach about 0.03–0.07 feet [0.01–0.02 metres] long. Small yellow flower structures, called cyathia, form between the spine pairs. They sit in short horizontal groups and leave small scars. Flowering peaks in spring and autumn but can occur outside those seasons. The fruit forms a small capsule with three clear angles. The seeds are round and smooth.

Grow this plant in full sun and soil that drains freely. It also tolerates some shade, and young plants can grow indoors. Use an open mix made mostly from mineral materials. Pumice and lava grit are suitable parts of that mix. Add only a small amount of peat or leaf mould. Water through active growth, from March to September. Do not let water collect around the roots. Keep the mix almost dry through winter.

LLIFLE describes this species as easy to grow and moderately fast-growing. It can form a large landscape plant within five to ten years. Its clumped form suits a dry garden as a specimen. Choose a site sheltered from strong winds. Wind can knock the stems together and leave lasting scars. Established plants can remain in the same place for years.