Euphorbia pseudocactus
| Light | Bright light to full sun; a little more sun brings out the banding |
|---|---|
| Water | Sparingly in growth; keep dry and rested through winter |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above about 5 °C; frost-tender, USDA zones 9b–11 |
| Propagation | Stem cuttings (allow the latex to seal and callus first) |
| Toxicity | Toxic — milky latex irritates skin and eyes (see Euphorbia) |
Euphorbia pseudocactus is a branching, cactus-like succulent from South Africa, named for its resemblance to a true cactus despite belonging to the unrelated genus Euphorbia. It forms clumps of upright, angular, jointed stems marked with handsome yellow-green cross-banding along the ridges, and is edged with short paired spines. It is grown widely as an easy, sculptural houseplant. A distinct variegated plant with zig-zagging stems is also popular in the succulent trade, sold as Euphorbia pseudocactus 'Zig Zag, though its identity is uncertain and it is often regarded as a hybrid rather than a true form of the species.
Description
Euphorbia pseudocactus grows into a shrubby, much-branched succulent, in time forming a dense clump up to around a metre tall. The stems are strongly angled — usually three- or four-sided — and constricted at intervals into segments, giving the plant a jointed, candelabra-like habit. Each ridge carries a repeating pattern of pale yellow-green chevrons or bands over a darker green ground, the feature that makes the species so recognisable.
Along the horny margins of the ridges sit small paired spines, which are modified stipules rather than the areole-borne spines of a true cactus. As in most euphorbias the flowers are tiny and enclosed in specialised structures called cyathia, borne along the ridge margins; they are yellowish and far less showy than a cactus bloom. All parts of the plant exude a milky white latex when cut or bruised.
Distribution and habitat
The species is native to South Africa, where it grows in warm, dry, largely frost-free thornveld and thicket, chiefly in KwaZulu-Natal. It favours well-drained ground and copes with long dry spells by storing water in its succulent stems, growing among other drought-adapted shrubs and succulents.
Cultivation
Euphorbia pseudocactus is one of the more forgiving columnar euphorbias and makes an undemanding container or landscape plant in warm climates. Grow it in a very free-draining, mostly mineral mix and give it bright light to full sun; strong light keeps the growth compact and deepens the yellow-green banding, while too little light makes the stems thin and dull. Water thoroughly when the soil has dried out during the warm months, then reduce watering sharply and keep the plant dry and cool through winter, when it is prone to rot if kept damp and cold.
It is frost-tender and should be protected from temperatures much below about 5 °C. See Watering and Repotting for general technique.
A note of caution: like all euphorbias, this plant bleeds a milky latex that is a skin and eye irritant and is toxic if ingested. Wear gloves and eye protection when pruning or repotting, keep the sap away from your face, and site the plant out of reach of children and pets. See the Euphorbia genus page for more on handling the latex safely.
Propagation
Propagation is easy from stem cuttings. Cut a healthy branch at a natural constriction, then rinse or blot the cut to stop the flow of latex and let the cutting dry and callus for several days to a week before setting it in a dry, gritty mix to root. Cuttings root readily in warm conditions. Wear gloves throughout, as the latex will flow freely from both the cutting and the parent plant.
Cultivars
A variegated plant with strikingly patterned, zig-zagging stems is widely sold as Euphorbia pseudocactus 'Zig Zag. Its exact identity is uncertain — it is often treated as a hybrid rather than a true selection of the species — but it is cultivated in the same way. Because variegated tissue carries less chlorophyll, it tends to be slower-growing and generally appreciates bright light without harsh midday scorch to keep its colours strong and its growth healthy.
Common problems
- Rot — the usual cause of loss, almost always from overwatering, a poorly draining mix, or cold damp conditions in winter; affected stems soften, blacken and collapse.
- Etiolation — too little light produces thin, weak, pale stems that lose the tight banded character.
- Pests — mealybugs (white fluff in the crevices and at the base) and spider mites are the most frequent offenders; see Pests and diseases.
- Cold damage — even a light frost can scar or kill the stems, so bring plants under cover before winter in marginal climates.
See also
- Euphorbia — the genus overview
- Propagation — cuttings · Soil and potting mix · Watering · Repotting · Pests and diseases