Euphorbia esculenta
| Light | Bright light to full sun; some afternoon shade in the hottest climates |
|---|---|
| Water | Moderate in the growing season; keep dry in winter, allowing the mix to dry fully between waterings |
| Soil | Very free-draining mineral mix (see Soil and potting mix) |
| Temperature | Best kept above freezing, but tolerates brief, light frost when dry (reportedly to about −5 °C); roughly USDA zones 9a–11 |
| Propagation | Seed (the species is monoecious, so a single plant can set seed) or stem cuttings, though cuttings seldom rebuild the domed caudex |
| Toxicity | Latex is a skin and eye irritant — avoid contact, wear gloves when cutting, and wash off any sap. Comparatively mild for a euphorbia (the plant is browsed by stock, hence the name "esculenta", edible), but still handle the sap with care |
Euphorbia esculenta is a medusoid succulent from South Africa that forms a large, low, dome-shaped central hub ringed by many slender, radiating finger-like branches. The stout swollen caudex sits mostly at ground level, and from its crown emerge dozens of tapering green arms that spread outward like the tentacles of a medusa, giving the plant its characteristic starburst silhouette. It is known in Afrikaans as the vingerpol ("finger cushion"), and belongs to the large and diverse genus Euphorbia.
Description
Euphorbia esculenta grows from a thick, woody caudex that is largely buried, presenting a broad domed hub at the soil surface. From the raised centre a dense whorl of cylindrical branches radiates outward, each arm a few millimetres to as much as about 2 cm thick and tapering to a point. The branches are usually simple and unbranched, patterned with small tubercles, and can number in the dozens on an established plant, forming a low mounded cushion that may reach a substantial spread with age.
Small cyathia (the specialised euphorbia "flowers") appear in woolly clusters near the tips of the arms, greenish-yellow and modest in size; each cluster bears both pollen-shedding anthers and seed-bearing stigmas, so — like the other medusoid euphorbias — the plant is monoecious and a single specimen can set seed. All parts of the plant contain a copious white latex.
Distribution and habitat
The species is native to the arid Karoo of South Africa, chiefly in the Eastern Cape (roughly from the Uitenhage district north to Jansenville, Graaff-Reinet and Somerset East), where it grows in dry, open, rocky ground under a hot, low-rainfall climate. In habitat the swollen caudex is drawn down into the soil so that only the finger-like crown is exposed, an adaptation that helps the plant survive drought, heat and grazing.
Cultivation
Euphorbia esculenta is a slow, tough, and rewarding plant for the collector, but like most caudiciform euphorbias it is intolerant of excess moisture. Grow it in a very free-draining, mostly mineral mix in a pot that accommodates the caudex, in bright light to full sun. Water when the soil has dried out during the warm growing season, then reduce watering sharply and keep the plant dry through the cool months to prevent rot. It tolerates light winter frost when kept dry, but protect it from hard or prolonged freezes.
Growers often plant it with the top of the caudex at or just above soil level to show off the domed hub, though in habitat it sits lower. See Watering and Repotting for general technique. Take care when handling: the latex is irritating to skin and especially to the eyes.
Propagation
Seed gives the best-formed, caudex-bearing plants and is the preferred method. The species is monoecious, so a single plant can self-pollinate and set seed, although germination can be slow. Sow fresh seed on a warm, gritty, mineral surface kept lightly humid until germination. The radiating arms can also be removed and rooted as cuttings — they strike fairly readily but rarely rebuild the handsome domed caudex of a seed-grown plant, so seed is preferred for form. See Propagation — seed and Propagation — cuttings for full walkthroughs.
Common problems
- Rot — the commonest cause of loss, almost always from overwatering, a slow-draining mix, or watering while cold; the caudex or arms soften and discolour.
- Etiolation — too little light makes the arms grow thin, long and pale, losing the tight cushion form.
- Pests — mealybugs (white fluff among the arms and at the crown) and root mealybugs are the usual culprits; watch also for scale.
- Latex irritation — not a plant problem but a grower one: the milky sap is an irritant, so wear gloves and keep it away from your eyes when pruning or repotting.
See also
- Euphorbia — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Pests and diseases