Euphorbia caput-medusae
| Light | Bright light to full sun; tolerates some direct sun once established |
|---|---|
| Water | Sparingly in growth; keep dry through its dormant period |
| Soil | Very free-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep frost-free; USDA zones 9b–11 |
| Propagation | Seed; cuttings of the arms (see notes) |
| Toxicity | Toxic — milky latex is a skin, eye and mucous-membrane irritant; keep away from pets and children |
Euphorbia caput-medusae is a sprawling succulent from South Africa's Western Cape, and one of the classic "medusoid" euphorbias whose form inspired the name — a thick, knobbly central stem crowned by a writhing tangle of slender, tuberculate arms. The dense radiating branches, studded with small tubercles and topped with tiny flowers, give the plant the appearance of a mass of snakes, hence its common name Medusa's head. It is the archetypal "Medusa's head" euphorbia, and the informal medusoid group of the genus Euphorbia takes its name from this species.
Description
Euphorbia caput-medusae grows from a stout, partly buried main stem (caudex) that thickens with age. From the crown of this central body radiate numerous cylindrical arms, each covered in low, spirally arranged tubercles and tapering toward the tip. In older, well-grown specimens the arms can lie and curl over one another to form a low, sprawling mound.
Like most succulent euphorbias it is spineless but bleeds a copious white latex when cut or bruised — an irritant sap that should be handled with care. Small cyathia (the tiny cup-shaped false flowers typical of the genus) appear near the arm tips, their glands fringed with pale, cream to greenish-white processes, and are modest rather than showy. The plant is monoecious, so a single individual bears both male and female flowers.
Distribution and habitat
The species is native to the Western Cape of South Africa. It is largely coastal, occurring along the west coast southwards to the Cape Peninsula and eastwards along the south coast as far as Mossel Bay, on sandy flats and lowland slopes. It grows in a predominantly winter-rainfall region, drawing on cool, moist winters and enduring hot, dry summers — a rhythm that shapes how it is best watered in cultivation. In habitat the caudex often sits low in the ground with only the arms visible above the sand, giving the plant protection from heat and grazing.
Cultivation
E. caput-medusae is an undemanding and characterful plant for a collection, provided drainage is sharp and water is not overdone. Grow it in a gritty, mostly mineral mix in a pot that is not too large, in bright light or gentle direct sun to keep the arms compact rather than stretched. Water when the mix has dried out during the plant's active period, and ease off markedly when it rests; as a winter grower it appreciates a drier, warmer summer, though many growers keep it ticking over year-round with careful watering. Keep it frost-free and never let it sit in cold, wet soil, which invites rot.
Always wear gloves and eye protection when pruning or repotting, as the latex is a strong irritant. See Watering and Repotting for general technique, and Pests and diseases for routine care.
Propagation
The species can be raised from seed, which germinates on a warm, mineral surface and yields plants with the classic thick central caudex. Arms can also be removed and rooted as cuttings: allow the cut end to callus for several days first, and be mindful of the bleeding latex. Cuttings tend to produce more branching, offset-like plants rather than a single dominant caudex, whereas seed-grown plants develop the classic thick central stem.
Common problems
- Rot — the usual cause of loss, from overwatering, a poorly draining mix, or watering while dormant; the caudex or arm bases soften and discolour.
- Etiolation — too little light makes the arms thin, elongated and weak instead of stout and tightly radiating.
- Pests — mealybugs (white fluff among the tubercles and at the crown) and, in dry indoor air, spider mites are the most common.
- Latex irritation — not a plant problem but a grower one: the sap can cause painful skin and eye reactions, so handle with gloves.
See also
- Euphorbia — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — cuttings · Pests and diseases