Euphorbia decaryi
| Light | Bright, indirect light to a few hours of gentle sun; protect from harsh midday summer sun |
|---|---|
| Water | Moderate in growth; let the mix dry between waterings, keep drier and cooler in winter |
| Soil | Gritty, free-draining mix with added mineral matter (see Soil and potting mix) |
| Temperature | Warmth-loving; keep above about 10 °C, USDA zones 10–11 |
| Propagation | Division of rhizomes; stem cuttings; seed |
| Toxicity | Toxic; the milky latex is a skin and eye irritant, harmful if ingested |
Euphorbia decaryi is a small, mat-forming succulent from southern Madagascar that spreads by creeping underground rhizomes to form low, sprawling colonies. It is prized among collectors for its distinctive foliage — narrow leaves with crinkled, wavy or crisped margins that give each rosette a sculpted, almost reptilian texture. It belongs to the vast and varied genus Euphorbia.
Description
Euphorbia decaryi grows as a clustering, ground-hugging plant rather than an upright stem succulent. Thin, semi-woody stems creep along and just beneath the surface, arising from spreading rhizomes so that a single plant slowly builds into a dense mat. From the tips of these stems rise small rosettes of leaves.
The leaves are the plant's signature feature: narrow to spoon-shaped, dark green to bronze, and edged with pronounced wavy, crinkled or crisped margins. Older leaves are shed from the lower stem, leaving a textured, corky trail behind the active growing tips.
Like other members of the genus, the true flowers are tiny and are carried in specialised cup-like structures called cyathia. In E. decaryi these are small and modest, greenish to reddish-brown, and easily overlooked against the striking foliage. As with all euphorbias, the plant contains a milky white latex that seeps from any cut or break.
Distribution and habitat
The species is endemic to southern Madagascar, where it grows in seasonally dry country among rock and sparse vegetation. Its rhizomatous, mat-forming habit suits an environment of intense light and irregular rainfall: the creeping stems and underground rhizomes let it spread into pockets of grit and hold on through dry spells.
Several closely related forms and varieties have been described from the same region, and wild Euphorbia populations in Madagascar face pressure from collection and habitat loss. Unusually for a succulent euphorbia, E. decaryi is listed on CITES Appendix I — the strictest level, shared by only a handful of highly threatened Madagascan euphorbias — rather than the Appendix II that covers most succulent euphorbias. International trade is therefore tightly regulated, and artificially propagated plants are the only responsible source; wild-collected material must not be bought or sold.
Cultivation
Euphorbia decaryi is one of the more forgiving Madagascan euphorbias, but its mat-forming roots and rhizomes dislike sitting wet. Grow it in a wide, shallow pot or pan filled with a gritty, very free-draining mix, and give it bright light — a spot with good light and a little gentle sun brings out the best leaf colour and the tightest, most crinkled growth. In weak light the rosettes stretch and the characteristic texture is lost.
Water moderately while the plant is in active growth, always letting the mix dry out before watering again, and cut back sharply through the cooler months to keep it barely moist. It is warmth-loving and frost-tender, so keep it above roughly 10 °C and out of cold, damp conditions that invite rot. See Watering and Repotting for general technique; a shallow pan makes it easier to divide crowded mats when repotting.
When handling, cutting or repotting the plant, protect your skin and eyes from the milky latex, which is a genuine irritant — wear gloves and wash any splashes off promptly.
Propagation
The easiest method is division: because the plant spreads by rhizomes, a healthy mat can be lifted and pulled or cut apart into rooted sections, each of which re-establishes readily. Stem cuttings can also be taken; let the cut latex dry and the wound callus before setting them in a gritty mix (see Propagation — cuttings).
The species can be raised from seed as well, though seed is less commonly available and plants are more usually shared by division among growers. Rinse or blot the latex from any fresh cut before it seals, as heavy weeping can slow rooting.
Common problems
- Rot — the most frequent cause of loss, almost always from a heavy, water-retentive mix or overwatering; stems and rhizomes soften and blacken.
- Etiolation — too little light makes the rosettes stretch, pale and lose their tightly crinkled leaf margins.
- Pests — mealybugs (white fluff among the stems and at the roots) and spider mites are the usual offenders; inspect the crowded centre of the mat where pests like to hide.
See also
- Euphorbia — the genus overview
- Propagation — offsets · Propagation — cuttings · Soil and potting mix · Watering · Repotting · Pests and diseases