Encephalartos sclavoi

Encephalartos sclavoi

Encephalartos sclavoi, Sclavo’s cycad, is a cycad from Tanzania with an upright trunk about 1 m tall, crowned with leaves nearly 2 m long whose broad, very leathery leaflets, with rolled-under margins, overlap like the slats of a half-open Venetian blind. This species of the genus Encephalartos, discovered by the French collector Jean-Pierre Sclavo and described at the end of the 1980s, grows only in the West Usambara Mountains, in and around Magamba Nature Reserve near Lushoto, in Tanga Region. It was long thought to be limited to a single site with fewer than 50 adult plants; a 2017 survey found a second, larger population, but fire, farming and collecting threaten it, and the IUCN assesses it as Critically Endangered (assessment published in 2024). In cultivation it is a vigorous species, but one with little tolerance of cold.

Key facts about Encephalartos sclavoi

  • Accepted name: Encephalartos sclavoi A.Moretti, D.W.Stev. & De Luca (1990), accepted by The World List of Cycads (version 2026.08.15), Species+ and GBIF; other sources cite “De Luca, D.W.Stev. & A.Moretti” (see Taxonomy)
  • Synonyms: none according to The World List of Cycads
  • Family: Zamiaceae, order Cycadales
  • Common names: Sclavo’s cycad (Species+)
  • Natural range: Tanzania, West Usambara Mountains (Lushoto District, Tanga Region), at Gologolo and Sungwi, in and around Magamba Nature Reserve
  • IUCN status: Critically Endangered (CR), assessment by S. Andrew and J.D. Bösenberg dated 13 March 2020 and published in 2024; Vulnerable (VU) in the IUCN action plan of 2003
  • CITES and other protection: CITES Appendix I since 1977, like the whole genus; Annex A in the European Union
  • Documented hardiness: −5.5 °C (22.1 °F) withstood in the ground at Fréjus (Var, south-east France), according to its owner (2013); two plants defoliated by frosts of −4 to −5 °C (24.8 to 23 °F) at the Jardin zoologique tropical, La Londe-les-Maures (Var), as reported on 20 January 2012; complete defoliation by frost, with a good chance of recovery, in Salento, southern Italy (2008); −1 °C (30.2 °F) without damage (Salento, 2009); see Cold hardiness
  • Light and soil: in the wild, steep, dry grassland slopes, ridges and rock outcrops surrounded by montane forest, with about 1,200 mm of rain a year; in cultivation, plenty of light and a very free-draining medium
  • Habit and adult size: upright trunk up to 1 m tall and 30 to 35 cm in diameter; leaves 1.75 to 2 m; male cones 20 to 25 cm, female cones 30 to 40 cm, yellow when mature (original description)
  • In the UK, US and Australia: Kew and Glasgow Botanic Gardens (BGCI); Montgomery Botanical Center (five accessions, 1994 to 2015), Fairchild, the Huntington, Lotusland, UC Berkeley, the New York Botanical Garden and others in the United States; Royal Botanic Gardens Victoria (wild-origin plant in an outdoor bed in Melbourne, planted in 2011), Sydney, Brisbane, Cairns and Adelaide in Australia
  • Toxicity: seeds toxic, as in all cycads (see Toxicity and precautions)

How to recognise Encephalartos sclavoi

Its authors regard it, in the field, as the most distinct species of central East Africa: its very leathery leaves and leaflets, with stiff, rolled-under margins, overlapping downwards like a half-open Venetian blind, make it “unmistakable”, even without cones. The original description (Stevenson, Moretti and De Luca, Delpinoa, 1987–1988) gives the following characters:

  • Trunk: upright, up to 1 m tall and 30 to 35 cm in diameter, covered with the bases of old leaves;
  • Leaves: 1.75 to 2 m long, oblong, gradually narrowed and spiny towards the base; petiole 10 to 15 cm, swollen and woolly at the base; rachis straight, glabrous or barely woolly;
  • Leaflets: the median ones alternate to almost opposite, very leathery, bluish green to dark green and yellow at their point of attachment, crowded and overlapping, with a median groove, 18 to 28 cm long and 4 cm wide; the pungent tip curves into a hook; each margin bears in its lower half none to three short teeth, often reduced to mere bumps, and is strongly rolled under; the lower leaflets become smaller, then are abruptly reduced to spines over the last three to five pairs;
  • Male cones: almost conical, yellowish green when young, then yellow, 20 to 25 cm long, on a stalk 2 to 4 cm long;
  • Female cones: cylindrical to ovoid-cylindrical, 30 to 40 cm long and 15 to 20 cm wide, green to yellow when young, then yellow to tawny, on a stalk 3 to 4 cm long.

In the wild in 2017, females bore one to three cones and males at most one; the larger female cones made it possible to tell the sexes apart (Andrew, report to the Mohamed bin Zayed Species Conservation Fund).

Encephalartos sclavoi
Encephalartos sclavoi grown at the Palmengarten in Frankfurt, Germany.

Jungle Music, a nursery in southern California, describes wide, sometimes cupped, very leathery leaflets with rolled margins, sometimes armed with marginal spines, and yellow to yellowish-green cones. It distinguishes two forms in cultivation: one whose new leaves emerge green, more vigorous, with longer, less cupped and less spiny leaflets; and one whose new leaves emerge reddish brown, with more cupped and more spiny leaflets, slower and less robust. These forms are a nursery’s observation, not recognised by any botanical publication. The same page gives stems of “two to four meters”, which contradicts both its own introduction (a trunk up to a metre) and the original description.

Hybrids

No natural hybrid of Encephalartos sclavoi is documented. In cultivation, hybridisation is possible whenever several species cone at the same time, especially with the related East African species often grown alongside it.

Possible confusion

The authors place the species in a group that includes Encephalartos bubalinus, Encephalartos gratus, Encephalartos hildebrandtii, Encephalartos tegulaneus and Encephalartos voiensis, now placed under Encephalartos kisambo (GBIF). It differs from them in its vegetative characters, its cones and its habitat, and above all in its broad, very leathery leaflets with rolled-under margins, arranged like a blind.

Taxonomy

The species was described from collections made by Jean-Pierre Sclavo. The type (Sclavo 2, holotype at Kew, isotype at the Missouri Botanical Garden) was collected on 4 January 1986 at Gologolo, near Lushoto, in Tanga District. The description appeared in two publications that list the authors in a different order: an article in Delpinoa, the journal of the Naples botanic garden (volume 29–30 dated 1987–1988, printing completed on 31 May 1989), under the name “Encephalartos sclavoi De Luca, D. Stevenson et Moretti”, and the Memoirs of the New York Botanical Garden (57: 156–161, 1990). The World List of Cycads follows the latter and cites “A.Moretti, D.W.Stev. & De Luca (1990)”, while the botanic gardens of Naples and Melbourne write “De Luca, D.W.Stev. & A.Moretti”. The correct author citation and date of valid publication were discussed by I. Claassen in the journal Encephalartos in 1994.

Etymology and history

The species is named after Jean-Pierre Sclavo, a French collector and connoisseur of Encephalartos, who discovered it, recognised it as new and provided the authors with his specimens, photographs and field notes (original description; Haynes, 2022, via The World List of Cycads). S.M. Andrew’s report gives a discovery date of 1998, which contradicts the collection date of the type (1986).

Common names

Species+ uses the English name Sclavo’s cycad, after the collector. No other name, in English or in a local language, is documented.

In the wild

Encephalartos sclavoi is endemic to the West Usambara Mountains, part of the Eastern Arc of Tanzania; the description places it in Tanzania near the Kenyan border. It grows in and around Magamba Nature Reserve (9,284 ha), in Lushoto District (Tanga Region), a reserve of submontane and montane forest, grassland and thicket between 900 and 2,250 m above sea level. According to S.M. Andrew’s project (2017), the species occupies high sites: steep, dry grassland slopes, ridges and rock outcrops surrounded by montane forest, where it tolerates dry conditions, with strong winds and dry soils. The reserve receives about 1,200 mm of rain a year, in two seasons (mid-March to May, then October to December); temperatures range from 15 to 21 °C (59 to 69.8 °F) from June to September and from 25 to 30 °C (77 to 86 °F) from October to December. Jungle Music describes the climate as “dry and hot”, a summary that these data only partly support.

Until 2017 the species was known only from Gologolo, with probably fewer than 50 adult plants according to the 2009 assessment. S.M. Andrew’s survey in 2017 (25 plots) found a second population, at Sungwi, with 474 plants (138 seedlings, 200 juveniles and 136 adults), but only 19 at Gologolo (no seedlings, 9 juveniles and 10 adults), pointing to a rapid decline of the known site. Females there were twice as numerous as males.

Conservation status and regulation

Encephalartos sclavoi is assessed as Critically Endangered (CR) on the IUCN Red List. The current assessment, by S. Andrew and J.D. Bösenberg, is dated 13 March 2020 and was published in 2024 (GBIF, Crossref). The World List of Cycads still cites the previous assessment by J.S. Donaldson (2010), CR under criteria B1ab(iii,v)+2ab(iii,v); C2a(i), that is, a tiny range, a very small population and a continuing decline. In 2003 the IUCN action plan (Donaldson, 2003) classed it only as Vulnerable, with an estimated population of 5,000 to 6,000 plants, a slight decline, habitat destruction and traditional use as threats, and no population in a reserve; these figures are very different from those of 2009 and 2017.

According to S.M. Andrew, 88% of the plants observed in 2017 showed signs of human disturbance: fire (51% of cases), cultivation (27%) and clearing for settlement (21%); fire, used to prepare fields, destroys seeds and seedlings. The project supported in 2017 by the Mohamed bin Zayed fund also cites illegal logging, gold panning and over-collection by traditional healers and by seed collectors.

Regulation, according to Species+ (consulted through its public API on 26 October 2026):

  • CITES: Appendix I since 4 February 1977, like the whole genus;
  • European Union: Annex A, current list in Regulation (EU) 2026/1383 (in force since 29 June 2026); negative opinion of the EU Scientific Review Group of 20 June 2011, confirmed on 7 February 2013 and still current, on artificially propagated plants imported from South Africa (source codes A and D).

Seeds are covered in the same way as plants. Any plant offered for sale must come from cultivation and carry the CITES documents required by the countries concerned (and, in the European Union, the EU documents). These notes do not replace the official texts: check Species+ and the national authorities before any purchase or import.

Growing Encephalartos sclavoi

No institutional cultivation sheet exists for this species. In the wild it lives at altitude, on dry, rocky slopes, in a climate that is cool for part of the year, with two rainy seasons. Collectors describe it as vigorous: in South Africa, a member of the French forum Fous de palmiers saw plants in the ground coning at five to seven years old in 2011 and 2012. It remains sensitive to cold and winter wet.

Outdoor and in-ground cultivation

In southern California, Jungle Music recommends full or partial sun on the coast, partial sun or filtered light inland, and filtered light or shade in desert areas. Unlike most central African species, it says, it needs a fast-draining soil and does not tolerate excess water: kept too wet, it tends to lose its leaves in winter and to rot. The nursery describes it as not the easiest to grow, a plant that needs room and suits the middle layer of a garden, under larger plants. In Australia, Royal Botanic Gardens Victoria grows a wild-origin plant in Melbourne, planted on 5 October 2011, in an outdoor bed. In south-east France, a collector at Fréjus (Var) reported in June and July 2013 that his plant, raised in Thailand at the Nong Nooch garden nursery, had been in the ground since 2008 or 2009, had seen snow and came through −5.5 °C easily, although young (Fous de palmiers forum). On the Côte Bleue (Bouches-du-Rhône), a collector who had just planted out almost all his cycads noted in April 2015 that a large plant had lost its only, already tired leaf during the winter, without frost; its caudex remained firm. At the municipal botanic garden in Nice, a plant photographed in April 2011 looked slightly yellowish to a forum member, perhaps from too much sun or an unsuitable soil.

Container cultivation

In the Var, a collector grew his plant in a pot under glass all year round, shaded in summer, in 2008, then outdoors in summer and in a heated glasshouse from November to the end of March; it produced a new crown in September–October 2009, a sucker in November 2011 and ten leaves in December 2011 and January 2012. In 2012 he ranked it second for vigour among his East African Encephalartos, after Encephalartos hildebrandtii, and thought it worth trying outdoors only in very sheltered spots on the Côte d’Azur (Fous de palmiers forum). A pot allows the plant to be kept dry and frost-free in winter in cool, wet climates.

In cultivation in the UK, US and Australia

BGCI PlantSearch lists 25 institutions holding the species. In the United Kingdom, Kew and Glasgow Botanic Gardens declare it. In the United States, the Montgomery Botanical Center (Coral Gables, Florida) lists five accessions, from 1994, 1995, 1996, 2001 and 2015, and pollinates its plants by hand (photograph published in 2017 by the IUCN Cycad Specialist Group); BGCI also lists Fairchild, the Huntington, Lotusland, Descanso Gardens, the San Diego Botanic Garden, the San Diego Zoo, UC Berkeley, the New York Botanical Garden, Phipps Conservatory in Pittsburgh and two Hawaiian gardens. In Australia, Royal Botanic Gardens Victoria and the Royal Botanic Garden Sydney list it in their online catalogues, and BGCI adds Brisbane (Mount Coot-tha), Cairns, Adelaide and the University of Melbourne System Garden. A BGCI listing records a declaration by the garden, not a living plant on display today. In Italy, the Naples botanic garden grew a specimen in 1993–1994 (Gaudio et al., 1997) and shows one in its Califano glasshouses in a publication of 2019 (Sibilio); the Messina botanic garden listed it in 2009. Jungle Music describes the species as rare, with sporadic availability and seed hard to obtain, but often offered in several sizes.

Propagation

No publication specific to the species deals with sowing. Cones appear early on vigorous plants: in South Africa, plants in the ground produced them at five to seven years old (Fous de palmiers, 2011 and 2012). In the wild, the Sungwi population had many seedlings in 2017, a sign that reproduction is still active. The plant can sucker from the base (Var, 2011). For sowing, the general rules for cycads apply (see the article on growing cycads from seed). Seeds and suckers are covered by CITES Appendix I, and no plant should be taken from the wild.

Pests and diseases

No pest specific to the species is documented. As with all Encephalartos, rot of the roots and caudex in a cold, waterlogged medium is the main risk in cultivation; Jungle Music confirms that the species rots if kept too wet. In the wild, S.M. Andrew mentions possible seed predation by weevils, without having measured it.

Cold hardiness

Encephalartos sclavoi comes from the tropical mountains of Tanzania. No institutional source publishes a cold-tolerance value; growers’ reports show that it can lose all its leaves to frost, then recover if the caudex stays sound. As with all Encephalartos, survivals in cold areas often concern young plants whose caudex is still small, protected by the thermal inertia of the soil; adult plants with an aerial trunk do not benefit from this protection.

Mediterranean and European experience

  • South-east France: at Fréjus (Var), a plant in the ground since 2008 or 2009 withstood −5.5 °C (22.1 °F) and snow according to its owner (2013), with no detail on the state of the foliage. The other plants reported in the Var are in pots and overwintered in a heated glasshouse. On the Côte Bleue (Bouches-du-Rhône), a large plant with a single leaf lost it during the winter of 2014–2015, without frost.
  • South-east France, Jardin zoologique tropical (La Londe-les-Maures, Var): the plant, with glaucous foliage, was to be protected over the winter of 2008–2009, as the species was “perhaps not among the hardiest”; in early January 2009, after a low of −3 °C (26.6 °F), it was still doing well, whereas another Encephalartos of undetermined species had damaged leaves despite a bubble-wrap cover. On 20 January 2012 the garden judged its hardiness poor: frosts of −4 to −5 °C (24.8 to 23 °F) had defoliated two plants, which were then brought back into growth in a glasshouse; it considered the species worth trying outdoors only in very sheltered spots on the Var coast (Le Lavandou, Saint-Clair, Le Rayol, Giens).
  • Southern Italy: in Salento (Apulia), a collector counted Encephalartos sclavoi in December 2008 among the species that frost defoliates completely but that have a good chance of recovering in spring; in December 2009 his plants came through a night at −1 °C (30.2 °F) without damage (Tropicamente forum).

This Mediterranean experience is relevant to readers in comparable climates, such as coastal California and southern Australia: a very sheltered position and a dry winter soil are needed, and a sharp frost is likely to defoliate the plant.

United Kingdom, United States and Australia

  • United States: Jungle Music grows and recommends the species for southern California gardens, without giving temperatures; it notes winter defoliation in soil that stays too wet.
  • Australia: a wild-origin plant has grown outdoors in Melbourne since 2011 (Royal Botanic Gardens Victoria census), without published winter data.
  • United Kingdom: no hardiness data have been published; the British gardens that declare the species do not say whether it is grown outdoors, and a heated glasshouse is the safe choice.

The USDA hardiness values that circulate for this species rest on no published measurement; no USDA zone is documented for Encephalartos sclavoi in a reliable source.

Toxicity and precautions

Like other cycads, Encephalartos sclavoi contains toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a toxin affecting the liver and the nervous system; the seeds are the most dangerous part. No study deals with the toxicity of this particular species, but the plant should not be regarded as harmless. Keep plants and seeds out of reach of children and pets. If any part is swallowed, contact a poison centre, a doctor or a vet without delay.

Traditional uses

The species is collected by traditional healers in the Usambara Mountains (S.M. Andrew’s project, 2017), and the IUCN action plan of 2003 already counted traditional use among its threats. The nature of these uses is not specified.

Frequently asked questions

Where does Encephalartos sclavoi grow?

Only in the West Usambara Mountains of Tanzania, in and around Magamba Nature Reserve near Lushoto, at Gologolo and at Sungwi.

How many are left in the wild?

The 2009 assessment spoke of fewer than 50 adult plants at Gologolo. In 2017 a survey found only 10 adults there, but discovered at Sungwi a population of 474 plants, including 136 adults.

Who was Sclavo?

Jean-Pierre Sclavo, a French collector and connoisseur of Encephalartos, who discovered the species, recognised it as new and provided the material for its description.

How can it be recognised?

By its broad, thick, very leathery leaflets with rolled-under margins, which overlap like the slats of a half-open Venetian blind, and by its yellow cones.

Is it frost-hardy?

Only slightly. A plant in the ground withstood −5.5 °C (22.1 °F) at Fréjus, in south-east France, but others lose all their leaves to frost, as did two plants at the Jardin zoologique tropical in La Londe-les-Maures at −4 to −5 °C (24.8 to 23 °F) (reported in January 2012). In cool climates, growing it in a pot overwintered under glass is the safest choice; in the ground, it should be tried only in a very sheltered position in a frost-free or nearly frost-free climate.

Does it grow fast?

Yes, for an Encephalartos: in South Africa, plants in the ground coned at five to seven years old, and a plant in a heated glasshouse in the Var produced ten leaves at once.

Can seeds or plants be bought?

Only if raised in cultivation and accompanied by the required CITES (and, in the EU, EU) documents.

Is it poisonous?

It should be treated as such, like all cycads, especially its seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Stevenson, D.W., Moretti, A. & De Luca, P. (1987–1988, printed in 1989). Encephalartos sclavoi De Luca, D. Stevenson and Moretti (Zamiaceae), a new species from Tanzania. Delpinoa n.s. 29–30: 3–5. [Original description.]
  • Moretti, A., Stevenson, D.W. & De Luca, P. (1990). Encephalartos sclavoi. Memoirs of the New York Botanical Garden 57: 156–161. [Publication followed by The World List of Cycads.]
  • Claassen, I. (1994). Encephalartos sclavoi: correct author citation and date of valid publication. Encephalartos 37: 9. [Cited in the bibliography of Encephalartos no. 139 (2022).]
  • Slabbert, R. & Hurter, P.J.H. (1994). Focus on Encephalartos sclavoi. Encephalartos 37: 4–8. [Cited by The World List of Cycads and Donaldson (2003).]
  • Donaldson, J.S. (ed.) (2003). Cycads. Status Survey and Conservation Action Plan. IUCN/SSC Cycad Specialist Group, Gland and Cambridge. [VU status in 2003, numbers.]
  • Donaldson, J.S. (2010). Encephalartos sclavoi. The IUCN Red List of Threatened Species 2010 (amended version of 2017): e.T41924A114568376. [Previous assessment, cited by The World List of Cycads and S.M. Andrew.]
  • Andrew, S. & Bösenberg, J.D. (2024). Encephalartos sclavoi. The IUCN Red List of Threatened Species 2024: e.T41924A51044974. [Current assessment, cited by GBIF and Crossref.]
  • Andrew, S.M. (undated). Distribution, population structure and threats of an endangered cycad Encephalartos sclavoi in Tanzania. Report to the Mohamed bin Zayed Species Conservation Fund (2017 survey).
  • Gaudio, L., Aceto, S., Caputo, P., Cozzolino, S., Siniscalco Gigliano, G., Moretti, A. & De Luca, P. (1997). Enzyme polymorphism in Encephalartos Lehmann (Zamiaceae). Delpinoa n.s. 35–36 (1993–1994): 55–64. [Specimen grown in Naples.]
  • Sibilio, G. (2019). The greenhouses of the Botanical Garden of Naples, Italy. Delpinoa n.s. 56–57 (2014–2015): 69–103. [Plant in the Califano glasshouses.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Etymology, via The World List of Cycads.]
  • Calonje, M., Stevenson, D.W. & Osborne, R. (2026). The World List of Cycads, version 2026.08.15. Montgomery Botanical Center, Coral Gables. doi:10.5281/zenodo.21958524 [Reference checklist; consulted.]