Euphorbia abdelkuri Balf.f. (1903) is one of the most extraordinary and coveted species in the entire Euphorbia genus — and one of the rarest. Endemic to a single locality on the tiny island of Abd al Kuri in the Socotra Archipelago (Yemen), this spineless, columnar succulent looks like a cluster of melted grey candles rising from the desert rock. Its stems are ash-grey with a wrinkled, waxy epidermis unlike any other euphorbia, and — most remarkably of all — it exudes yellow latex when cut, the only species in the genus known to produce anything other than white sap. Reduced to as few as four surviving clumps in the wild by 1967, Euphorbia abdelkuri is severely threatened and represents one of the most extreme cases of island micro-endemism in the plant kingdom. In cultivation, it is grown almost exclusively grafted onto Euphorbia canariensis rootstock and commands extraordinary collector prices, particularly the pink-flushed cultivar ‘Damask.’
Taxonomy and Nomenclature
Euphorbia abdelkuri was described by the Scottish botanist Isaac Bayley Balfour in 1903, published in Forbes’s The Natural History of Sokotra and Abd-el-Kuri (pages 528–530), with a preliminary mention in the Report of the British Association (Glasgow, 1901, page 854). The specific epithet abdelkuri directly references the plant’s only known home: the island of Abd al Kuri (also spelled Abd el Kuri), the westernmost island of the Socotra Archipelago.
Within the genus Euphorbia, the species is classified in subgenus Euphorbia, among the succulent columnar species, though its exact sectional placement has been debated. Its morphology is unlike any other described Euphorbia, making comparative taxonomy difficult.
According to Plants of the World Online (POWO, Kew), Euphorbia abdelkuri has no accepted synonyms. The native range is given simply as Socotra (Abd al Kuri).
Common names: no widely established common name exists in English, though “Abdelkuri spurge” and informal designations like “grey ghost” or “candle euphorbia” are sometimes used. The cultivar ‘Damask’ is sometimes called the “pink ghost.”
The Only Euphorbia with Yellow Latex
Among the more than 2,000 species of Euphorbia, virtually all produce a white (or occasionally transparent when dried) milky latex when wounded. Euphorbia abdelkuri is the sole known exception: its latex is distinctly yellow. This unique biochemical trait has been noted since the earliest botanical descriptions and remains unexplained. The latex is highly toxic and poisonous, consistent with the irritant diterpene chemistry of other Euphorbia species, but the pigment responsible for the yellow coloration has not been definitively characterised.
This yellow sap is not merely a curiosity — it is one of the most reliable diagnostic characters for confirming the identity of Euphorbia abdelkuri, particularly in distinguishing genuine specimens from superficially similar grey-bodied euphorbias that occasionally appear in the trade.
Description and Morphology
Euphorbia abdelkuri is a succulent shrub that forms densely branched, candelabra-like clumps, typically reaching approximately one metre in height and 1.5 metres in diameter, though exceptional specimens in habitat have been reported up to three metres tall with equivalent spread.
Stems
The stems are the plant’s defining glory: columnar, spineless, more or less cylindrical, approximately 5 cm in diameter, with generally six ribs bearing slightly raised, conical tubercles. The epidermis is thick, waxy, and strikingly greenish-grey to ash-grey or tan — the overall effect is that of a cluster of grey candles with drips of melted wax running down the sides. This wrinkled, worn-looking “skin” is unique among cultivated euphorbias and immediately recognisable. The stems branch from the base and occasionally dichotomously (splitting into two equal branches at the tip).
Spines
None. Euphorbia abdelkuri is completely spineless — a rare condition among the succulent columnar euphorbias, most of which bear at least vestigial spines. The absence of spines, combined with the grey epidermis, gives the plant an alien, almost mineral quality that sets it apart from all other species in the genus.
Leaves
The leaves are tiny, deciduous, and rarely observed. They appear briefly at the growing tips during favourable conditions and fall almost immediately.
Flowers
The cyathia are small, approximately 5 mm in diameter, with yellowish nectar glands, borne on short peduncles toward the tops of the stems. Flowering is exceedingly rare in cultivation — most sources report that Euphorbia abdelkuri has never been reliably documented to flower outside its native habitat.
Distribution and Habitat: A Single Mountain on a Tiny Island
The distribution of Euphorbia abdelkuri is among the most restricted of any succulent plant species on Earth. It is endemic to a single locality — the Quatar Saleh (also known as Jebel Hassala) — on the island of Abd al Kuri, the smallest inhabited island of the Socotra Archipelago, located in the Indian Ocean between the Guardafui Channel (Horn of Africa) and the Arabian Sea.
Abd al Kuri is a semi-desert island of approximately 133 km², largely devoid of vegetation, with a sparse human population of around 300 people. The island lies approximately 105 km west-southwest of the main island of Socotra. Euphorbia abdelkuri grows on limestone outcrops and granitic gravel slopes at elevations of approximately 150 to 270 metres (some sources cite up to 450 m for the historical range), where the plants form open thickets.
The Socotra Archipelago as a whole is recognised as a UNESCO World Heritage Site (inscribed 2008) for its extraordinary biodiversity and endemism — approximately 37% of the archipelago’s plant species are found nowhere else on Earth. Euphorbia abdelkuri is one of the most emblematic examples of this extreme island endemism.
Conservation: From Abundance to Four Clumps
The conservation story of Euphorbia abdelkuri is one of alarming decline. In the past, the species was reportedly much more abundant, growing across a ridge from approximately 150 to 450 metres elevation. By the time the Greek-South African botanist John Jacob Lavranos visited Abd al Kuri in 1967 and published his observations in the Cactus and Succulent Journal of America (1971), the species had been reduced to only four surviving clumps.
The reasons for this catastrophic decline remain obscure. Livestock do not browse the plant because of its highly toxic latex. Climate change, drought, or some pathological factor may be involved, but no definitive explanation has been established. The species was included in the IUCN Plant Red Data Book (1978) as a severely threatened taxon.
The current IUCN assessment lists Euphorbia abdelkuri as Vulnerable (VU). Under CITES, it is listed in Appendix II as part of the succulent Euphorbia genus listing, without any specific exemptions.
The species’ survival in the wild depends on the protection of its single known habitat and on the maintenance of ex-situ cultivated populations, which serve as an insurance policy against extinction. Every cultivated specimen of Euphorbia abdelkuri — whether the grey type or the ‘Damask’ cultivar — traces its origin, directly or indirectly, to the handful of clumps on Quatar Saleh.
The ‘Damask’ Cultivar
Euphorbia abdelkuri ‘Damask’ is a cultivar that appeared in 1999 as a spontaneous sport (somatic mutation) on an otherwise typical grey plant in cultivation. It differs from the standard form in its pinkish-reddish body coloration, which varies in intensity with light levels — brighter pink in strong light, more subdued under lower light conditions.
The colour behaviour has interesting characteristics: grey colouring is typically confined to whole or half ribs, and the change in bicoloured plants is always for red to replace grey, never the reverse. Some branches may produce entirely grey ribs, creating a striking two-toned effect. New growth tends to be brighter pink, gradually maturing to the grey-pink hue characteristic of the clone. The cultivar is propagated exclusively by vegetative means (grafting or cuttings) to maintain the colour mutation.
‘Damask’ has become one of the most sought-after cultivated euphorbias in the world, with prices for grafted specimens regularly reaching several hundred euros. Crested forms (Euphorbia abdelkuri f. cristata) also exist and are even rarer.
Cultivation and Care
Euphorbia abdelkuri is considered one of the most difficult euphorbias to grow on its own roots. Its slow growth, sensitivity to overwatering, and reluctance to root from cuttings have led to the near-universal practice of grafting.
Grafting
The species is grown almost exclusively grafted onto Euphorbia canariensis rootstock, which has proven to be the most compatible and vigorous stock. Grafting technique follows the standard Euphorbia method: wash all latex thoroughly from both cut surfaces (this is critical — residual latex prevents tissue fusion), cut a matching flat surface on scion and stock, hold together with elastic bands in a cross pattern over the plant and under the pot, and leave in an airy, shaded location for 7–10 days. Both scion and stock should be in active growth at the time of grafting.
Euphorbia resinifera has also been used as rootstock, but Euphorbia canariensis remains the preferred choice among specialist growers.
Light
Full sun to bright light. In its native habitat, Euphorbia abdelkuri grows fully exposed on rocky slopes in one of the most arid environments on Earth. In cultivation, provide maximum light. The ‘Damask’ cultivar develops its best pink coloration under intense light; in low light, it tends toward a duller grey-pink.
Temperature and Cold Hardiness
Euphorbia abdelkuri is strictly tropical with no frost tolerance whatsoever. It is rated for USDA hardiness zones 10b to 11b (minimum approximately +1.7 °C / 35 °F). Temperatures below 10 °C for prolonged periods should be avoided. In all non-tropical climates, the species must be grown in a heated greenhouse or as a carefully managed indoor specimen in the brightest possible position.
Watering
Water very sparingly. During the growing season (spring through autumn), water only when the substrate has dried completely — the semi-desert origin of this species means it expects long dry periods. In winter, keep almost completely dry. Overwatering is the primary cause of death in cultivation, causing root and stem rot that is often fatal before symptoms become visible. When in doubt, do not water.
Substrate
An extremely well-draining mineral mix is mandatory — even more mineral-heavy than a standard cactus blend. A mix of 70–80% pumice, perlite, or coarse volcanic gravel with 20–30% composted organic matter is appropriate. Pure mineral substrates are also used successfully by specialist growers.
Growth Rate
Extremely slow. Euphorbia abdelkuri is among the slowest-growing euphorbias in cultivation. Patience is not just recommended — it is essential. Specimens take many years to develop into the characteristic clumping candelabra form.
Pests and Problems
The species is largely pest-free. Root rot from overwatering is the overwhelming primary threat. Mealybugs can occasionally settle between the ribs. Grafted specimens require monitoring of the graft union for signs of deterioration.
⚠ Safety disclaimer. The yellow latex of Euphorbia abdelkuri is highly toxic — potentially more so than the white latex of most other euphorbias, given its unique chemical composition. All handling must involve gloves and eye protection. Contact with skin causes severe irritation; contact with eyes can cause intense pain and potential corneal damage. The latex should never be ingested under any circumstances.
Sources
- Balfour, I.B. (1903). Angiospermae. In: Forbes, H.O. (ed.), The Natural History of Sokotra and Abd-el-Kuri. The Free Public Museum, Liverpool, pp. 528–530. [Original species description]
- Lavranos, J.J. (1971). The island of Abd al Kuri and its peculiar Euphorbia. Cactus and Succulent Journal of America 43: 109–111.
- Lucas, G. (1978). The IUCN Plant Red Data Book. IUCN, Gland.
- Govaerts, R., Frodin, D.G. & Radcliffe-Smith, A. (2000). World Checklist and Bibliography of Euphorbiaceae (and Pandaceae) 1–4: 1–1622. The Board of Trustees of the Royal Botanic Gardens, Kew.
- Eggli, U. (2002). Illustrated Handbook of Succulent Plants: Dicotyledons. Springer.
- Buddensiek, V. Sukkulente Euphorbien. [Cultivation notes on E. abdelkuri]
Authority Pages
iNaturalist: Euphorbia abdelkuri
POWO — Plants of the World Online, Royal Botanic Gardens, Kew: Euphorbia abdelkuri Balf.f.
IUCN Red List — International Union for Conservation of Nature: Euphorbia abdelkuri — Vulnerable (VU)
CITES — Convention on International Trade in Endangered Species: Euphorbia abdelkuri — Appendix II
GBIF — Global Biodiversity Information Facility: Euphorbia abdelkuri Balf.f.
LLIFLE — Encyclopedia of Living Forms: Euphorbia abdelkuri