Euphorbia viguieri aka Viguiers Spurge

Euphorbia viguieri, or Viguier’s spurge, belongs to the spurge family. It comes from northern and central Madagascar. This succulent shrub grows in a seasonally dry tropical climate. It lives in open coastal woods and dry deciduous forest. Plants grow in sun or part shade on worn limestone. Humus gathers in cracks in the rock, where roots grow.

The plant has a spiny stem and sheds its leaves. Its form varies, but most plants have one unbranched stem. It reaches about 2.6 feet [0.8 metres] tall. Larger plants can reach 4.9 feet [1.5 metres]. The bright green stem narrows at its base. It has five or six angles, with raised ridges. Pale leaf scars and uneven rows of spines mark these ridges. The spines have broad bases that split into finer points. Though it looks like a cactus, it is not one.

Simple oval leaves gather near the stem tips on short stalks. They are deep green, with red near their bases. Raised white veins mark their lower sides. Each leaf ends in a small, sharp point. Plants tend to lose their leaves in winter under cultivation. Flower clusters form near the stem tips. Two bright red bracts frame each cyathium, the small flower unit. Cyathia may contain one sex or both sexes. Some plants bear only one sex. The fruit is a capsule with three chambers. Each chamber holds one seed, which the ripe fruit throws out.

Grow this slow-growing plant in bright light with some light shade. Strong summer sun can be too harsh. Too much shade leads to weak, pale, stretched stems. Outdoor growing suits tropical and subtropical climates. Young plants can also grow indoors. Give roots an open mix that drains well but holds some moisture. A little lime gravel suits the potting mix. Protect the plant from frost. The source advises winter nights near 54°F [12°C] and warmer days.

Water well during growth, then let the mix dry somewhat. Cut back watering in winter, when excess water can cause rot. Leave space around plants so air can move through them. Feed in spring with low-nitrogen fertilizer, but stop in winter. Its angular stems and red bracts give it ornamental value. Seed is the stated means of propagation.