Encephalartos delucanus

Encephalartos delucanus is a small cycad with a very short trunk, no more than 12 cm tall, endemic to western Tanzania, where it grows around Mpanda, in what is now the Katavi region. This species of the genus Encephalartos was described in 1992 by François Malaisse, Jean-Pierre Sclavo and C. Crosiers and named after the Neapolitan botanist Paolo De Luca. The IUCN lists it as Endangered. It is one of the least known species of the genus: only male plants have been described, and its cultivation is documented only in a Thai botanic garden.

Key facts about Encephalartos delucanus

  • Accepted name: Encephalartos delucanus Malaisse, Sclavo & Crosiers (1992), according to The World List of Cycads
  • Former names and synonyms: none; identified by its authors with the “Encephalartos sp. C (Mpanda)” mentioned by Heenan in 1977
  • Family: Zamiaceae, order Cycadales
  • Common names: none attested, in English or in any other language
  • Natural range: western Tanzania, Katavi region (Mpanda district)
  • IUCN status: Endangered (EN), assessment dated 18 March 2020 and published in the IUCN Red List 2024-1; the previous assessment (October 2009, published in 2010) had already listed it as Endangered under criteria B1ab(iii,v)+2ab(iii,v)
  • CITES and other protection: CITES Appendix I since 1977, like the whole genus; Annex A in the European Union, with a negative EU opinion on imports from South Africa
  • Documented hardiness: no data (see Cold hardiness)
  • Light and soil: wooded savanna and open grassland, recorded at 1500 and 1950 m (original description); requirements in cultivation not documented
  • Habit and adult size: erect trunk up to 12 cm tall and 10 to 20 cm in diameter; six to nine leaves 50 to 65 cm long; male cones 10 to 12 cm long (original description, 1992)
  • In the UK, US and Australia: declared to BGCI only by the Montgomery Botanical Center in Florida (accession of 2006)
  • Toxicity: not studied for this species; a documented risk for the genus (see Toxicity and precautions)

How to recognise Encephalartos delucanus

Encephalartos delucanus is a small plant with a very short trunk and a few green leaves whose narrow leaflets overlap towards the base of the leaf. The original description, published in Latin in the Annales de Gembloux (Malaisse, Sclavo and Crosiers, 1992), gives the following characters:

  • Trunk: erect, up to 12 cm tall and 10 to 20 cm in diameter; scale leaves (cataphylls) lanceolate, 30 to 40 mm by 10 mm, brown and hairless on the inner face, covered with a dense felt of grey-chestnut hairs on the outer face;
  • Leaves: six to nine, green, held at an angle of 60 to 80°, oblong, 50 to 65 cm long, abruptly narrowed at the base and recurved at the tip; petiole up to 45 mm long and 7 to 8 mm wide, covered with straw-grey hairs 3 to 4 mm long and blackish-brown hairs 1 mm long; rachis downy at the base, hairless at the top, marked above with two dark green lines;
  • Leaflets: 50 to 75 (66 on average) per leaf, inserted on the upper side of the rachis and overlapping towards the base; the median ones subopposite or alternate, green, oblong, 130 to 146 mm long and 12 to 14 mm wide (at least 11 mm), gradually tapering to a sharp point, with a yellow, narrowed (4 mm) and decurrent base and 13 to 19 parallel veins; two to four small yellow spines 4 to 5 mm long on the upper margin, two to five on the lower margin, and a terminal spine 2 to 4 mm long; towards the base the leaflets decrease abruptly: two to four are forked and the last two to six are reduced to spines;
  • Male cones: one or two, shortly stalked (stalk 1 to 1.5 cm when dry), ellipsoid to subcylindrical, yellowish green when young then green, 10 to 12 cm long and 2 to 3 cm wide when dry; about 55 scales, the median ones 12 to 14 mm by 9 to 11 mm;
  • Female cones and seeds: unknown to the authors, who saw only male plants.

Hybrids

No natural or cultivated hybrid of Encephalartos delucanus is documented.

Possible confusion

Confusion is possible with the other species of what Turner, Sclavo and Malaisse (2006) call the “Encephalartos poggei complex”: Encephalartos poggei, Encephalartos marunguensis, Encephalartos schmitzii and Encephalartos schaijesii, all from south-central Africa and all with no trunk or a short one. As early as 1992, the original description placed the species in this group of species with a very short trunk and medium-sized leaves, found from Angola to Tanzania, adding that Encephalartos delucanus, Encephalartos poggei, Encephalartos schmitzii and Encephalartos marunguensis are easily told apart, particularly by their leaves. According to Turner, Sclavo and Malaisse (2006), these species look alike in habit but are distinguished without ambiguity by their cones (colour, shape of the scales) and their leaves (leaflets, angle of the leaves and leaflets). According to The World List of Cycads, Encephalartos delucanus is the only one of these species known from Tanzania, so a plant in a collection should come with a record of its origin.

On the French Fous de palmiers forum, in 2011, a member suggested the name Encephalartos delucanus for a plant photographed in South Africa; the suggestion, made without examining the plant, shows how hard the small central African species are to identify from photographs.

Taxonomy

Encephalartos delucanus is accepted by The World List of Cycads. The species was described by François Malaisse, Jean-Pierre Sclavo and C. Crosiers in the first article of a series entitled “Recherches sur les Encephalartos Lehm. (Zamiaceae) d’Afrique centrale”, subtitled “Un nouvel Encephalartos de Tanzanie”, in the Annales de Gembloux (98(2): 153–157). The World List of Cycads dates the name to 1992 but cites the article as 1993 in its list of references; Turner, Sclavo and Malaisse (2006) date it to 1992, and the header of the article reads “Annales de Gembloux 1992, 98: 153–157”. Species+ spells the last author’s name “Croisiers”.

The type (holotype), collected by Sclavo under number 180, comes from the former Western Province of Tanzania, Mpanda district, at Mgoga, 30 km south of Katambike (5°45′ S, 31°30′ E); it is kept at Meise Botanic Garden (BR). It is a male plant collected in wooded savanna south of the Ugalla river. The authors cite three other collections, all male: the Kasima mountains, north-east of Katuma (6°19′ S, 30°42′ E), in wooded savanna (Sclavo 20, BR); Mount Sitebi (6°06′ S, 30°38′ E), at 1950 m, in open grassland (Kielland 21, EA); and the Lugala hills, at 1500 m (Kielland 22, EA). They identify the species with the “Encephalartos sp. C (Mpanda)” that Heenan (1977) had mentioned from Kielland’s collections. The species has no synonym. The second article of the series, in 1993, showed how useful leaf morphology is for telling the central African species apart.

Etymology and history

The epithet honours Professor Paolo De Luca (1944–2021), professor of botany at the Federico II University of Naples and director of the Naples botanic garden, in recognition of his work on cycads (original description; Haynes, 2022, followed by The World List of Cycads). De Luca himself described, with Moretti and Stevenson, another Tanzanian species, Encephalartos sclavoi.

The history of the species is poorly known. An article by Ian Turner, “In search of Encephalartos delucanus”, published in 1995 in the journal of the Cycad Society of South Africa (Encephalartos 44: 9–12), deals, judging by its title, with the search for the species in the field; the article, in a journal reserved for members, has not been consulted.

Common names

No common name is attested, in English or in any other language: Species+ gives none, and no Tanzanian vernacular name is recorded.

In the wild

Encephalartos delucanus is known only from Tanzania, in the Katavi region according to The World List of Cycads, around Mpanda. The original description gives the known localities: Mgoga south of the Ugalla river, the Kasima mountains, Mount Sitebi and the Lugala hills, the last two at 1950 and 1500 m; the habitats recorded are wooded savanna and, on Mount Sitebi, open grassland. The collector Kielland considered the plant very rare: on Mount Sitebi he had seen two groups of about twenty plants, 300 m apart. Turner, Sclavo and Malaisse (2006) describe, for the whole Encephalartos poggei complex, savannas and open woodland under a climate with a dry season of four to seven months, on permeable or rocky soils.

In 2003, the IUCN action plan for cycads (Donaldson, 2003) estimated the population at fewer than 1000 plants, in slight decline, and cited reproductive failure as a threat, together with a severe reduction of habitat. Pollinators and seed dispersers are not documented.

Conservation status and regulation

Encephalartos delucanus is listed as Endangered (EN) on the IUCN Red List. The current assessment, by the Eastern Arc Mountains and Coastal Forests CEPF Plant Assessment Project and J.D. Bösenberg, is dated 18 March 2020 and was published in the Red List 2024-1, with no change of category (GBIF and Crossref, consulted on 26 October 2026; these sources do not give its criteria). The previous assessment, by J.S. Donaldson, dated October 2009 and published in 2010, is the one still cited by The World List of Cycads: it listed the species as Endangered under criteria B1ab(iii,v)+2ab(iii,v), that is a restricted extent of occurrence and area of occupancy, few locations, and a continuing decline in habitat quality and in the number of mature plants. The species had been listed as Vulnerable in 1997 and in the 2003 action plan, which also recorded it in botanic garden collections, with no gene bank.

Like every species of the genus, it has been listed in CITES Appendix I since 4 February 1977, and in Annex A in the European Union (Regulation (EU) 2026/1383, applicable since 29 June 2026). Notably, the EU Scientific Review Group has held since 2013 a negative opinion on imports from South Africa of artificially propagated plants (source codes A and D), with no size limit, whereas for several related species it accepts small caudices. Species+ consulted on 26 October 2026: check the regulations in force.

Be wary of seed offers. In January 2011, a member of the Italian Tropicamente forum reported receiving from a seller who claimed to be from Cameroon an offer of “large quantities” of seeds of several rare species, including Encephalartos delucanus and even Encephalartos woodii, of which no female plant is known: an obviously fraudulent offer.

Growing Encephalartos delucanus

The cultivation of Encephalartos delucanus is documented by a single reliable source, from Thailand. At the Nong Nooch Tropical Botanical Garden, the curator of the cycad collection wrote in 2022 that the “seasonal deciduous species”, Encephalartos delucanus among them, thrive there and cone every year, in raised beds filled with half sand, a quarter compost and a quarter coarse gravel.

Outdoor and in-ground cultivation

Outside the tropics, no outdoor planting is documented. Given its origin in tropical savanna, a frost-free climate is the safe assumption, but no source gives a temperature limit; a raised, very free-draining bed like those of Nong Nooch is the only documented planting method.

Container cultivation

No container-growing report has been published. The general rules for tropical grassland Encephalartos apply: a deep pot, a mineral, free-draining mix, and reduced watering while the plant is without leaves or resting. In Europe, the species appears only in collection photos posted in 2017 on the Fous de palmiers forum, without any location or growing conditions; the poster reported that the imported plant had coned for the first time that year.

In cultivation in the UK, US and Australia

  • United States: the Montgomery Botanical Center (Coral Gables, Florida) holds one accession, received in 2006 according to its accession number, and is the only institution declaring the species to BGCI.
  • United Kingdom and Australia: no garden declares the species to BGCI, and no other source mentions it there.

A listing in BGCI shows a declaration by the garden, not necessarily a living plant today. In Italy, despite the dedication to a Neapolitan botanist, no source reports the species in the Naples botanic garden.

Propagation

Propagation is by fresh, fertile seed, but no female plant has been described and seeds of guaranteed origin are practically unobtainable. No data specific to the species is documented on germination or offsets. Seeds, like plants, fall under CITES Appendix I.

Pests and diseases

No disease or pest specific to Encephalartos delucanus is documented. As with other Encephalartos, root rot threatens plants kept too wet, particularly during rest.

Cold hardiness

No cold-hardiness data exists for Encephalartos delucanus. As with other Encephalartos, survivals in cold areas often concern young plants whose caudex is still underground, protected by the thermal inertia of the soil and sometimes by snow; nothing of the kind is documented for this tropical species, and adult plants do not benefit from this protection.

Mediterranean and European experience

No outdoor result is documented in France or Italy. Readers in Mediterranean climates, or in comparable climates such as coastal California or southern Australia, should treat it as a plant for a heated glasshouse, kept dry during its rest, until outdoor trials are documented.

United Kingdom, United States and Australia

The only published observation comes from the lowland tropical climate of Nong Nooch, in Thailand, where the species thrives. No cold value is documented elsewhere, and no USDA hardiness zone is given for the species in any source.

Toxicity and precautions

No toxicity data specific to Encephalartos delucanus is documented, but the risk is documented for the genus: Encephalartos are toxic, and their seeds particularly so. The toxicity of one species of the genus, Encephalartos horridus, was demonstrated as early as 1944 by Van der Walt. Cycads contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a compound that affects the liver, the digestive tract and the nervous system. For another cycad, the sago palm (Cycas revoluta), the ASPCA reports vomiting, black stools, jaundice, bleeding gastroenteritis, liver damage and deaths in dogs, cats and horses.

Wear gloves to handle seeds and their fleshy coat, and 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

No traditional use of Encephalartos delucanus is documented.

Frequently asked questions

Where does Encephalartos delucanus grow?

Only in western Tanzania, in the Katavi region, around Mpanda. The type was collected at Mgoga, 30 km south of Katambike, and the other known localities are the Kasima mountains, Mount Sitebi and the Lugala hills.

Who was De Luca?

Paolo De Luca (1944–2021), professor at the University of Naples, director of its botanic garden and a specialist in cycads. He himself co-described another Tanzanian species, Encephalartos sclavoi.

Is it threatened?

Yes. The IUCN has listed it as Endangered since 2010, a category kept in the assessment published in 2024. In 2003 the population was estimated at fewer than 1000 plants, with failing reproduction and a severely reduced habitat.

Are female plants known?

Not in the published literature. The original description of 1992 is based on four male collections, and the female cones and seeds were unknown to its authors; no later description of them is documented.

Can it be bought?

Rarely, and only with CITES documents. The species is in Appendix I and the European Union has a negative opinion on imports from South Africa, even of propagated plants. Be wary of offers of seeds in quantity, which are often fraudulent.

Is it hardy?

No, or at least nothing suggests it: no cold data exists. As a tropical African species, it should be kept frost-free, in a heated glasshouse.

Is it poisonous?

Yes, it should be treated as poisonous. No study deals with this species, but toxicity is demonstrated in the genus and cycad seeds contain cycasin.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Malaisse, F., Sclavo, J.-P. & Crosiers, C. (1992). Recherches sur les Encephalartos Lehm. (Zamiaceae) d’Afrique centrale. 1. Un nouvel Encephalartos de Tanzanie. Annales de Gembloux 98(2): 153–157. [Protologue; Latin description and measurements, type and other collections, altitudes, rarity, etymology, group of related species. Primary literature.]
  • Turner, I. (1995). In search of Encephalartos delucanus. Encephalartos 44: 9–12. [Cited by Donaldson (2003).]
  • Turner, I., Sclavo, J.-P. & Malaisse, F. (2006). Un nouvel Encephalartos Lehm. (Zamiaceae) de Zambie. Biotechnologie, Agronomie, Société et Environnement 10(3): 181–183. https://popups.uliege.be/1780-4507/index.php?id=1014 [Encephalartos poggei complex, habitats, references of 1992 and 1993.]
  • Donaldson, J.S. (ed.) (2003). Cycads. Status Survey and Conservation Action Plan. IUCN/SSC Cycad Specialist Group, Gland and Cambridge. [Vulnerable, fewer than 1000 plants, reproductive failure, ex situ collections.]
  • Donaldson, J.S. (2010). Encephalartos delucanus. The IUCN Red List of Threatened Species 2010: e.T41914A10593284. [EN, assessment dated 31 October 2009; cited by The World List of Cycads; superseded by the 2024 assessment.]
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project & Bösenberg, J.D. (2024). Encephalartos delucanus. The IUCN Red List of Threatened Species 2024: e.T41914A50905358. https://doi.org/10.2305/IUCN.UK.2024-1.RLTS.T41914A50905358.en [Current assessment (EN), dated 18 March 2020; authors and date read on Crossref, category on GBIF.]
  • Lindstrom, A. (2022). The cycad collection at Nong Nooch Tropical Botanical Garden, Thailand. CYCADS 6(1): 5–9. IUCN/SSC Cycad Specialist Group. [Growing Encephalartos in a tropical climate.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. https://doi.org/10.11646/phytotaxa.550.1.1 [Etymology of the epithet, via The World List of Cycads.]
  • Van der Walt, S.J. (1944). Recent investigations into the toxicity of plants, etc., in the Union of South Africa. Onderstepoort Journal of Veterinary Science and Animal Industry 20(1). [Toxicity of Encephalartos horridus; genus-level data.]
  • Calonje, M., Stevenson, D.W. & Osborne, R. (2026). The World List of Cycads, version 2026.08.15. Montgomery Botanical Center, Coral Gables. https://doi.org/10.5281/zenodo.21958524 [Reference checklist; consulted.]