Encephalartos kisambo

Encephalartos kisambo is a large tree-like cycad from south-eastern Kenya, where it grows in the Maungu Hills near Voi, in Taita-Taveta County, in a dry evergreen mist forest between 800 and 1,050 m. Described in 1989 by Robert B. Faden and H. J. Beentje, this species of the genus Encephalartos bears the name the Taita people give it, kisambo. It forms a trunk 1 to 2 m tall and about 50 cm across, crowned with green leaves 2.4 to 3.6 m long with sickle-shaped leaflets, and creamy yellow male cones up to 64 cm long. It was also described the same year as Encephalartos voiensis, and the Tanzanian plants published as Encephalartos kanga are now included in it. It is listed as Endangered. In cultivation it is vigorous but needs space and warmth.

Key facts about Encephalartos kisambo

  • Accepted name: Encephalartos kisambo Faden & Beentje (1989), accepted by The World List of Cycads (version 2026.08.15), Species+ and GBIF
  • Former names and synonyms: Encephalartos voiensis Moretti, D.W.Stev. & Sclavo (1989); Encephalartos kanga Pócs & Q.Luke (2007 or 2008 depending on the source); “Encephalartos sp. B (Voi)” of Heenan (1977)
  • Family: Zamiaceae, order Cycadales
  • Common names: Voi cycad (Species+, Haynes 2009); kisambo, the local name in the Taita language (Faden and Beentje, 1989)
  • Natural range: Kenya, Taita-Taveta County (Maungu or Nyangala Hills), with records from Kasigau and Sagala needing confirmation; The World List of Cycads adds Tanzania (Kilimanjaro region, and Morogoro through Encephalartos kanga)
  • IUCN status: Endangered (EN), assessment published in 2024 (Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project and J. D. Bösenberg); already EN in 2010 and in the IUCN action plan of 2003
  • CITES and other protection: CITES Appendix I (whole genus, since 1977); Annex A in the European Union, with a negative EU opinion on artificially propagated plants from South Africa
  • Documented hardiness: no reliable value for an adult plant; in Italy, a plant left outdoors survived, badly damaged, about −2 °C (28.4 °F) and snow in the winter of 2014–2015 (see Cold hardiness)
  • Light and soil: in the wild, dry evergreen mist forest and steep slopes with dry scrub; in cultivation, sun or partial shade and a free-draining soil
  • Habit and adult size: trunk 0.9 to 2.2 m tall and 45 to 52 cm across, rarely several stems; leaves 2.4 to 3.6 m; male cones 49 to 64 cm, female cones 42 to 45 cm (Faden and Beentje, 1989)
  • In the UK, US and Australia: Kew (BGCI); Fairchild, Lotusland, the Huntington, Berkeley, the San Diego gardens, Naples, Selby, the New York Botanical Garden and others in the United States; Melbourne (outdoor beds), Brisbane, Adelaide and Townsville in Australia
  • Toxicity: seeds poisonous, as in all cycads (see Toxicity and precautions)

How to recognise Encephalartos kisambo

Look for large green leaves with crowded, overlapping, sickle-shaped leaflets whose upper margin carries three to five prickles grouped near the base, and for long, cylindrical, creamy yellow male cones. The original description by Faden and Beentje (1989) gives the following characters:

  • Trunk: 0.9 to 2.2 m tall and 45 to 52 cm across, upright or leaning, rarely several stems (up to 12); leaf scars rhomboid, 12.5 to 15 cm wide
  • Leaves: clustered at the top, 2.39 to 3.60 m long and 51 to 76 cm wide, with 89 to 96 pairs of leaflets; petiole base swollen, sometimes covered with felted brown hairs
  • Leaflets: median leaflets crowded and overlapping, inserted every 2.5 to 3 cm, lanceolate-oblong and sickle-shaped, 24 to 37.5 cm long and 2.9 to 3.7 cm wide, leathery, with a sharp tip and rolled-under margins; upper margin with 3 or 4 (sometimes 5) prickles, all within the first 7 cm; lower margin without a prickle or with a single one; the lowest leaflets reduced to palmate, then forked, then single prickles
  • Male cones: cylindrical, 49 to 64 cm long and 10 to 12.5 cm across, creamy yellow when ripe, sometimes curved, on a stalk 15 to 32 cm long covered with dark brown down
  • Female cones: clustered, cylindrical, 42 to 45 cm long and about 16 cm across, pale yellow or orange when ripe
  • Seeds: with an orange-yellow coat, ellipsoid, 3 to 3.9 cm long and 1.7 to 2.5 cm wide

The measurements reported by Heenan in 1977, before the description, point the same way: a trunk up to 2.2 m that tapers upwards, a strongly swollen rachis base that leaves characteristic scars on the trunk, and leaves up to 3.7 m long; plants growing in the open reached only two-thirds of the size of those growing in partial shade under the forest (Heenan, 1977, quoted by Haynes, 2009).

Encephalartos kisambo
A plant of Encephalartos kisambo at the Jardín de Aclimatación de La Orotava (Tenerife, Canary Islands).

Hybrids

No natural or garden hybrid of Encephalartos kisambo is documented. In cultivation, Holzman (2009) notes that young seedlings look very much like those of Encephalartos hildebrandtii, which makes a reliable label essential, and seed from collections where both species cone may not be pure.

Possible confusion

The closest species, according to its authors, is Encephalartos hildebrandtii, of the coasts of Kenya and Tanzania, which grows at lower altitudes. Faden and Beentje (1989) separate Encephalartos kisambo from it by its sickle-shaped leaflets with fewer teeth, its male cones usually larger with less strongly reflexed scales, its shallower female cone scales and its orange-yellow, not red, seeds. Encephalartos tegulaneus, of central Kenya, has smaller, more widely spaced leaflets which may carry two teeth on the lower margin; Encephalartos bubalinus has smaller leaves and leaflets and much smaller male cones.

In the key published by Haynes (2009), adapted from Moretti and colleagues (1989), Encephalartos kisambo stands apart from the neighbouring species of East and Central Africa by median leaflets ending in a single sharp point, slightly to clearly sickle-shaped, 24 to 37 cm long, on leaves over 2 m long with a short petiole or none; Encephalartos sclavoi, of Tanzania, has leaves 1.7 to 2 m long and leaflets with a hooked tip.

Taxonomy

Robert B. Faden (Smithsonian Institution, Washington) and H. J. Beentje (East African Herbarium, Nairobi) described the species in 1989 in the Kenyan journal Utafiti (2(1): 7–10). The type was collected on 26 December 1971 in the Maungu (Nyangala) Hills, at 1,025 m, in dry evergreen mist forest (Faden et al. 71/965, holotype at Kew, K; isotypes at BR, EA, MO, PRE, UPS, US and WAG). The authors also cite collections by P. G. Archer (March and May 1970) and by T. D. Willing and E. J. Robertson (1985) in the same hills.

The same year, A. Moretti, D. W. Stevenson and J.-P. Sclavo described Encephalartos voiensis (Annals of the Missouri Botanical Garden 76: 934–938) from collections by Sclavo, apparently unaware of Faden and Beentje’s description (Haynes, 2009). Published later, that name is a synonym of Encephalartos kisambo.

Faden and Beentje already mentioned a sterile collection by T. Pócs from the Kanga Mountains in Tanzania, which they did not think conspecific in the absence of cones. Pócs and Q. Luke described these plants as Encephalartos kanga (Journal of East African Natural History 96: 193–201; dated 2007 by Haynes and Species+, 2008 by The World List of Cycads), acknowledging their resemblance to Encephalartos kisambo. Haynes (2009) placed the name in synonymy, citing a high degree of overlap in vegetative characters, the lack of male cone data and female cone characters based on a single plant; CITES adopted this treatment at its 17th Conference of the Parties, applied in 2017 (Species+). A molecular study (Treutlein and colleagues, 2005, cited by Haynes) places the species close to the Encephalartos that are nearest to it in geography and morphology.

Etymology and history

The epithet is kisambo, the name of the plant in the language of the Taita, the people of the hills of the same name (Faden and Beentje, 1989; Haynes, 2022, cited by The World List of Cycads).

The species was found in 1970 near Voi by Archer, then at the East African Herbarium in Nairobi, as his collections cited in the original description show; other authors had suggested 1973 or Heenan’s expeditions of 1973–1974 (Haynes, 2009). The first published mention is Heenan’s (1977), as “Encephalartos sp. B (Voi)”. As early as 1989, Faden and Beentje wrote that it had already been collected “in considerable numbers” by non-Kenyans for sale to collectors, and called for its complete protection.

Common names

In English the species is known as the Voi cycad (Species+, Haynes, 2009), after the town near the Maungu Hills. Kisambo is the local name in the Taita language (Faden and Beentje, 1989).

In the wild

In 1989 Encephalartos kisambo was known with certainty only from a very small area of the Maungu Hills, in Taita-Taveta County, south-eastern Kenya: according to the label of one of Archer’s collections, the population covered about 160 hectares. Heenan (1977) had also reported it from Kasigau and Sagala, two other hill massifs of the region, but Faden and Beentje considered those records in need of confirmation. The World List of Cycads and Species+ now list Kenya and Tanzania (Kilimanjaro region, and Morogoro for the plants described as Encephalartos kanga); the published sources do not describe the Tanzanian populations of the Kilimanjaro region.

It grows in a low, dry evergreen forest bathed in mist, on the summit and on the south-eastern and eastern slopes of the hills, with Craibia, Drypetes gerrardii, Manilkara discolor or Cussonia holstii, and more rarely on steep, exposed slopes covered in dry scrub, between 800 and 1,050 m. Epiphytes grow on its trunks: Impatiens walleriana, Streptocarpus caulescens and the fern Davallia chaerophylloides. This small forest also holds the only Kenyan sites of two orchids (Faden and Beentje, 1989). No data have been published on its pollinators or on the dispersal of its seeds.

Conservation status and regulation

Encephalartos kisambo is Endangered (EN) on the IUCN Red List. The current assessment, published in 2024 (version 2024-1, dated 31 August 2023 according to Crossref), is by the Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project and J. D. Bösenberg (GBIF, Crossref). The previous assessment (October 2009, published in 2010) already listed it as Endangered, under criteria B1ab(ii,iii)+2ab(ii,iii), that is, a very small range and a decline in the area occupied and in the quality of the habitat; The World List of Cycads still cites it. In 2003 the IUCN action plan listed it as Endangered, with about 5,200 plants in the wild, a rapid decline due to collecting, habitat destruction and traditional uses, and no population in a protected area (Donaldson, 2003). In 2009 a Kenyan grower cited the clearing of bush for subsistence farming and the cutting of forest for charcoal (Cameron, 2009). According to a BGCI report (2020), the species is among the threatened trees of the Taita Hills and is the best represented of the region’s threatened species in collections, with 25 ex situ collections recorded worldwide.

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

  • CITES: Appendix I since 4 February 1977, like the whole genus; seeds are covered as well as plants;
  • European Union: Annex A, current list in Regulation (EU) 2026/1383; for artificially propagated plants from South Africa, a negative opinion covering the whole genus, issued on 3 December 2010, was lifted on 11 March 2011; a negative opinion specific to the species, issued on 20 June 2011 under the name Encephalartos kanga, was confirmed on 7 February 2013 and remains in force, and has applied to Encephalartos kisambo since the two names were merged in 2017.

These notes do not replace the official texts: check Species+ and the legislation in force before any purchase or import, and ask for documents proving that a plant was propagated in cultivation.

Growing Encephalartos kisambo

Encephalartos kisambo has become a fairly common species in private and public collections (Haynes, 2009). Published reports describe it as vigorous and easy, but demanding in space. They all come from warm climates with little or no frost (Kenya, Hawaii, southern California); in cooler regions it is a large plant for a heated glasshouse or a big container.

Outdoor and in-ground cultivation

At Athi River, Kenya, at 1,450 m, fifteen plants set in the ground in 2002 grew clearly faster in the sun, with 9 to 11 leaves per flush against 3 to 7 in the shade; after seven years the largest had a caudex 40 cm across and leaves 2.5 m long, with no particular disease or pest (Cameron, 2009). In Hawaii, Holzman (2009) describes flushes of 30 to 70 leaves 2.4 to 3.7 m long on some plants, leaves held very upright as they emerge and spreading later, and a plant that tolerates both dry and very wet soils and rarely suckers. Jungle Music, a cycad nursery in Encinitas, California, writes on an undated page that the species takes full coastal sun but prefers partial or filtered sun, and filtered light or shade inland and in the desert; that it is one of the few Encephalartos that like water, while tolerating a couple of weeks without; that a rich, acidic, loamy soil is ideal; and that its upright leaves and fast growth make it a popular green cycad; as it is large and spiny, the nursery advises keeping it away from paths and seating.

Container cultivation

In the Var, on the French Mediterranean coast, a collector followed a young Encephalartos kisambo in a pot on the Fous de palmiers forum: its caudex was 10 cm tall in May 2009, it flushed from August to October 2009, then again outdoors in spring 2013 and in August 2014. He overwinters his Encephalartos in a heated glasshouse and in 2012 ranked Encephalartos kisambo third for vigour among his East African species, after Encephalartos hildebrandtii and Encephalartos sclavoi. Container growing keeps the plant manageable for a while, but its leaves of 2 m or more soon need a large glasshouse.

In cultivation in the UK, US and Australia

The species is widely held by botanic gardens. In the United Kingdom, the Royal Botanic Gardens, Kew, declares it to BGCI PlantSearch. In the United States, Holzman (2009) first saw it in 1991 at Fairchild Tropical Botanic Garden in Florida, which lists it in its catalogue; Ganna Walska Lotusland, the Huntington, the University of California Botanical Garden at Berkeley, Descanso Gardens, San Diego Botanic Garden, the San Diego Zoo, Naples Botanical Garden, Marie Selby Botanical Gardens, the Edison and Ford Winter Estates, the New York Botanical Garden and two Hawaiian gardens declare it to BGCI. Montgomery Botanical Center lists no accession in its online catalogue. In Australia, the Royal Botanic Gardens Victoria grows it in outdoor beds at Melbourne Gardens (online census, 19 October 2026), and Brisbane Botanic Gardens Mount Coot-tha, the Botanic Garden of South Australia in Adelaide and James Cook University in Townsville declare it to BGCI. A BGCI listing shows that a garden has declared the species at some point, not that a plant is alive today.

Propagation

Seed is the documented method. Holzman (2009) finds the female cones easy to hand-pollinate; male plants cone every year, females rather every other year, and plants take longer to reach maturity than other Encephalartos of Central Africa because of the size of the caudex. The species rarely suckers (Holzman, 2009; Faden and Beentje, 1989, who record several stems only rarely); no published source describes the removal of suckers. Seeds are covered by CITES Appendix I as well.

Pests and diseases

No disease specific to the species is documented. In Hawaii, Holzman (2009) reports cones that rot and blacken before becoming receptive, and heart rot after the large leaf bases are cut too close; he advises shortening old leaves by only three-quarters at first. At Athi River, no pest or disease had been seen after seven years (Cameron, 2009).

Cold hardiness

No reliable cold tolerance is documented for an adult Encephalartos kisambo, and no temperature record from the Maungu Hills has been published. The few reports available come from Italy and concern brief frosts.

Mediterranean and European experience

In Italy, a collector in the Salento (Apulia) placed Encephalartos kisambo, in December 2008 and on the basis of good-sized, healthy plants, among the species that frost strips of all their leaves but that have a good chance of recovering in spring; in December 2009, after a night at −1 °C (30.2 °F) between two days close to 20 °C (68 °F), his plants had come through unharmed, without his saying whether they were in pots or in the ground (Tropicamente forum). Another Italian grower, whose town is not given, reported on the same forum in September 2015 that a plant left outdoors during the winter of 2014–2015, with lows of −2 °C (28.4 °F) and snow, and reduced to “an insignificant remnant”, had just produced a new leaf after a summer of watering. In France no reading has been published: the Var plant mentioned above is in a pot and spends the winter in a heated glasshouse. As in other Encephalartos, survival in the cold often concerns young plants whose caudex is still underground, protected by the thermal inertia of the soil and sometimes by snow; an adult plant with an aerial trunk does not enjoy that protection.

United Kingdom, United States and Australia

No dated cold report has been published from these countries. The outdoor plants at Melbourne show that the species can be grown in the open in a mild temperate climate, but the census does not record their winter history. No botanical source gives a USDA zone for the species; the zone ratings found on some websites cite no measurement. In Britain it needs a heated glasshouse.

Toxicity and precautions

No published study deals with the toxicity of Encephalartos kisambo in particular, but the risk is documented in other species of the genus, so it should not be considered harmless. Encephalartos, like other cycads, contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived; these substances affect the liver, the digestive tract and the nervous system, and the seeds are the most dangerous part. The ASPCA reports vomiting, diarrhoea, liver damage and deaths in dogs, cats and horses that have eaten cycads.

Wear gloves to clean seeds, keep plants and seeds out of reach of children and pets, and if any part is swallowed, contact a poison centre, a doctor or a vet without delay.

Traditional uses

The IUCN action plan (Donaldson, 2003) lists traditional uses among the threats to the species, without describing them; no published source says what they are. An Egyptian study of 2025 (El-Far and colleagues) compared the chemical composition and biological activity of Encephalartos kisambo and Encephalartos ferox grown in Egypt; only its title could be read.

Frequently asked questions

Where does Encephalartos kisambo grow?

In south-eastern Kenya, in the Maungu Hills near Voi (Taita-Taveta County), in a dry mist forest between 800 and 1,050 m. The World List of Cycads also records it from Tanzania, including the plants described as Encephalartos kanga.

What does kisambo mean?

It is the name of the plant in the language of the Taita, the people of the hills of south-eastern Kenya where it grows. Faden and Beentje took it unchanged as the species name in 1989.

Are Encephalartos voiensis and Encephalartos kanga the same plant?

Yes, according to The World List of Cycads and Species+. Encephalartos voiensis was described the same year as Encephalartos kisambo, but later; Encephalartos kanga, from Tanzania, was merged with it by Haynes in 2009, the differences being judged insufficient.

How can I tell it from Encephalartos hildebrandtii?

By the leaflets, cones and seeds. The leaflets of Encephalartos kisambo are sickle-shaped and carry fewer teeth, its male cones are usually larger and its seeds are orange-yellow, whereas those of Encephalartos hildebrandtii are red. Young seedlings of the two species look very alike.

How big does it get?

Big. In the wild it forms a trunk 0.9 to 2.2 m tall and about 50 cm across, with leaves 2.4 to 3.6 m long. In cultivation, large plants can push out 30 to 70 leaves at once, so it needs a lot of room.

Is it frost-hardy?

Hardly, and data are scarce. In Italy, plants took a night at −1 °C (30.2 °F) without damage in 2009, and a plant left outdoors survived −2 °C (28.4 °F) and snow in 2014–2015 but lost almost all its foliage. Outside frost-free climates, keep it under glass in winter.

Is it poisonous?

Yes, it should be treated as such, like all cycads. The seeds are the most dangerous part.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Faden, R.B. & Beentje, H.J. (1989). Encephalartos kisambo, a new cycad from Kenya, with a note on E. tegulaneus. Utafiti 2(1): 7–10. [Original description.]
  • Moretti, A., De Luca, P., Sclavo, J.-P. & Stevenson, D.W. (1989). Encephalartos voiensis (Zamiaceae), a new east central African species in the E. hildebrandtii complex. Annals of the Missouri Botanical Garden 76: 934–938. [Synonym; cited by Haynes (2009) and The World List of Cycads.]
  • Pócs, T. & Luke, Q. (2007). A new species of Encephalartos (Zamiaceae) from Tanzania. Journal of East African Natural History 96(2): 193–201. [Encephalartos kanga, synonym; dated 2008 by The World List of Cycads.]
  • Haynes, J.L. (2009). Taxonomic history, conservation status & morphologic affinities of Encephalartos kisambo Faden & Beentje. The Cycad Newsletter 32(1): 15–17. [Review.]
  • Haynes, J.L. (2009). Encephalartos kanga Pócs & Q. Luke — a newly described “red cone cycad” from Tanzania. The Cycad Newsletter 32(1): 6–14. [Synonymy; reasons quoted by The World List of Cycads.]
  • Cameron, A. (2009). Encephalartos kisambo in cultivation – Athi River, Kenya. The Cycad Newsletter 32(1): 17–18. [Cultivation in Kenya.]
  • Holzman, G. (2009). Growing kisambos in Hawaii. The Cycad Newsletter 32(1): 19–20. [Cultivation in Hawaii.]
  • Heenan, D. (1977). Some observations on the cycads of Central Africa. Botanical Journal of the Linnean Society 74: 279–288. [“Encephalartos sp. B (Voi)”; cited by Faden and Beentje and by Haynes.]
  • Donaldson, J.S. (ed.) (2003). Cycads. Status Survey and Conservation Action Plan. IUCN/SSC Cycad Specialist Group, Gland and Cambridge. [EN, 5,200 plants, rapid decline, threats.]
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project & Bösenberg, J.D. (2024). Encephalartos kisambo. The IUCN Red List of Threatened Species 2024: e.T41906A242271815. https://doi.org/10.2305/IUCN.UK.2024-1.RLTS.T41906A242271815.en [Current assessment (EN), cited by GBIF and Crossref.]
  • El-Far, S.S., El-Sherbeni, S.A., Ragab, A.E. & Ibrahim, S.M. (2025). Comparative preliminary phytochemical and biological investigations on Encephalartos kisambo Faden & Beentje and Encephalartos ferox G. Bertol. cultivated in Egypt. Journal of Advanced Medical and Pharmaceutical Research: 118–126. [Title read through Crossref.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. https://doi.org/10.11646/phytotaxa.550.1.1 [Etymology, cited by 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. https://doi.org/10.5281/zenodo.21958524 [Checklist.]