Encephalartos princeps

Encephalartos princeps, the Kei cycad, is a blue cycad endemic to the Great Kei River basin in the Eastern Cape of South Africa, where it grows on dolerite cliffs and outcrops. This species of the genus Encephalartos, described in 1965 by Robert Allen Dyer, forms clumps of upright trunks up to 3 m tall, sometimes reclining and 5 m long, topped with glaucous or silvery leaves recurved towards the tip. Long confused with Encephalartos lehmannii, it differs in its taller trunks, more crowded leaflets and clustered cones with warty scales. It is assessed as Vulnerable by the IUCN, threatened by collecting and habitat degradation. In western France, a young plant in the ground, under a cloche, came through frosts of −5 to −7 °C (23 to 19.4 °F) near Nantes in the winter of 2010–2011 without damage, while a plant died unprotected at −13 to −16 °C (9 to 4 °F) in North Carolina.

Key facts about Encephalartos princeps

  • Accepted name: Encephalartos princeps R.A.Dyer (1965), accepted by The World List of Cycads (version 2026.08.15), GBIF and Species+
  • Former names and synonyms: no synonym; the plants were previously included in Encephalartos lehmannii (Henderson’s “form D”, 1945)
  • Family: Zamiaceae, order Cycadales
  • Common names: Kei cycad (PlantZAfrica, Species+); keibroodboom in Afrikaans (PlantZAfrica)
  • Natural range: South Africa, Eastern Cape, middle and lower Great Kei River basin (Swart Kei and Kabousie valleys), on dolerite
  • IUCN status: Vulnerable (VU A4acd; B1ab(iii,v)), assessment by J.D. Bösenberg dated May 2020, published in 2022
  • CITES and other protection: CITES Appendix I since 1977, like the whole genus; Annex A in the European Union, with a positive EU opinion (2011) on artificially propagated plants from South Africa whose caudex does not exceed 15 cm in diameter
  • Documented hardiness: frost- and drought-resistant according to PlantZAfrica; −5 to −7 °C (23 to 19.4 °F) without damage in the ground under a cloche near Nantes, France (winter 2010–2011); −7 °C (19.4 °F) without damage in a pot in a cold glasshouse in Ravenna, Italy (winter 2009–2010); killed at −13 to −16 °C (9 to 4 °F) in North Carolina (winter 2013–2014) (see Cold hardiness)
  • Light and soil: full sun, any soil provided it is well drained and aerated, moderate watering (PlantZAfrica)
  • Habit and adult size: clumps of trunks 20 to 30 cm in diameter, upright to 3 m, rarely 4 m, or reclining and 5 m long with age; leaves 0.75 to 1.3 m
  • In the UK, US and Australia: Cambridge University Botanic Garden (accession of 2018) and Kew; Montgomery Botanical Center (1977 and 2018), Fairchild, the Huntington, Lotusland, the Missouri Botanical Garden, UC Berkeley and some fifteen other American gardens; Royal Botanic Garden Sydney and Adelaide in Australia (BGCI)
  • Toxicity: seeds toxic, as in all cycads (see Toxicity and precautions)

How to recognise Encephalartos princeps

It is a blue Encephalartos with trunks that are rather slender for their height, often several from the base, and crowded leaves recurved in their upper third. Dyer (1965, original description and Bothalia revision) and PlantZAfrica describe it as follows:

  • Stems: often branching from the base, up to 3 m tall, rarely 4 m, or up to 5 m long when they recline with age, 20 to 30 cm in diameter; PlantZAfrica speaks of clumps of 10 to 15 trunks
  • Leaves: 75 to 110 cm according to the original description, 1 to 1.3 m according to Dyer’s revision, fairly straight or recurved in the upper third, sometimes slightly twisted, glaucous, often bluish or silvery for a long time, hairy when young; petiole 15 to 21 cm, whose basal swelling (pulvinus), small and woolly, is often hidden by the trunk scales
  • Leaflets: linear-lanceolate, pungent, about 15 cm by 1 to 1.3 cm, entire or sometimes toothed on the lower margin, overlapping in a V in the upper third of the leaf; towards the base they are reduced to one or two spines
  • Cones: dull green, two to four per stem according to the original description (one to three per season according to PlantZAfrica), shortly stalked; male cones subcylindrical, 16 to 26 cm by 8 to 10 cm, with scales drawn out into a beak 1.2 to 1.5 cm long; female cones barrel-shaped, about 30 by 20 cm, rounded at the top, with scales irregularly covered with large papillae (warty) and scattered whitish or brownish hairs
  • Seeds: red, about 4 by 2 cm

According to PlantZAfrica, the cones appear in January; the males shed pollen from April to June, and the female cones disintegrate from October to December. Jungle Music, a nursery in southern California, describes a colour varying from powdery silver to turquoise blue, keeled leaves, mostly unarmed leaflets, green female cones and greenish-yellow and brown male cones; it gives a mature leaf length of a metre or less and notes that stems in cultivation rarely exceed 1 to 1.5 m.

Hybrids

No natural hybrid of Encephalartos princeps is reported: the “supposed hybrids” that Dyer (1965) mentions in the Eastern Cape concern Encephalartos trispinosus, further west. Dyer stresses that the ranges of Encephalartos princeps, Encephalartos lehmannii, Encephalartos trispinosus and Encephalartos horridus do not seem to overlap.

In cultivation, crosses exist: in July 2023 Jungle Music offered first-generation hybrids obtained by pollinating a female of a blue form of Encephalartos longifolius with pollen of Encephalartos princeps. On the French forum Fous de palmiers, a grower setting up a pollen bank in April 2014 deliberately excluded crosses between close species such as Encephalartos lehmannii × princeps, so as not to blur the lines. Seed from a garden where several species cone at the same time is not necessarily pure.

Possible confusion

The commonest confusion is with Encephalartos lehmannii, in which most authors placed the species before 1965. According to Dyer, Encephalartos princeps grows taller, with relatively slender trunks; its young leaves are often hairy and its leaflets more crowded, overlapping in the upper third of the leaf; it bears two or more cones per stem, against usually one in Encephalartos lehmannii; the face of its female cone scales is warty, whereas it is almost smooth in Encephalartos lehmannii; and its pulvinus is smaller, often hidden, whereas that of Encephalartos lehmannii is large, visible and surrounded by a reddish-brown collar. The two species do not grow on the same rocks: dolerite for Encephalartos princeps, sandstone for Encephalartos lehmannii. Dyer adds that either may carry a few teeth on the lower margin of the leaflets, so this character does not separate them. Jungle Music likewise points to the cones, the size of the stems and the angle at which the leaflets are attached.

On a young plant without cones, identification remains difficult. On the Italian forum Tropicamente, in August 2012, a grower learnt that a plant sold as Encephalartos princeps was rather, according to another member, an Encephalartos lehmannii, because its upper leaflets were well spaced; a year later the new leaves overlapped and the question remained open. In southern Corsica, a grower who thought he had a female Encephalartos princeps recognised in July 2013, when distributing its seed, that it was Encephalartos trispinosus, under a name received with the plant (Fous de palmiers forum). Encephalartos trispinosus is recognised by its leaflets, which often carry one or two spiny lobes on the lower margin, and grows mainly on shales, further west.

Encephalartos friderici-guilielmi grows with it in the south-east of the Queenstown district, but confusion is unlikely according to Dyer, and impossible with cones: those of Encephalartos friderici-guilielmi are very woolly. In Dyer’s key, Encephalartos eugene-maraisii, another blue species, differs in its leaves curving inwards near the tip rather than outwards.

Taxonomy

Encephalartos princeps is an accepted name in The World List of Cycads, GBIF and Species+. Robert Allen Dyer described it in 1965 in the Journal of South African Botany (volume 31, issue 2, pp. 111–112, plate 19), in a paper on new species and type specimens of South African Encephalartos. The type was collected by Ernest Galpin on 16 April 1911 (Galpin 8090), among dolerite rocks on the lower slopes of the Swart Kei valley, at Junction Farm, between 2,300 and 2,600 ft (about 700 to 790 m), together with Encephalartos friderici-guilielmi; the holotype is in Pretoria, an isotype at the South African Museum. Earlier, the specimens were referred to Encephalartos lehmannii by Hutchinson and Rattray (1933) and formed “form D” of Encephalartos lehmannii in Henderson (1945). Dyer divided Henderson’s broad concept of Encephalartos lehmannii into three species, Encephalartos lehmannii, Encephalartos trispinosus and Encephalartos princeps, leaving a remainder of uncertain origin, including supposed hybrids. No variety is recognised, and the name has not changed since 1965.

Etymology and history

The Latin epithet princeps means “first”: Dyer chose it because he thought the species had a longer history and a more stately habit than its near relatives, Encephalartos lehmannii and Encephalartos trispinosus (Haynes, 2022, via The World List of Cycads). In his 1965 revision he specifies that the idea that it arose earlier in evolution than its Eastern Cape relatives remains speculation. The genus name Encephalartos means “bread in the head”, a reference to the starchy pith of the trunk.

In 2014 The Cycad Newsletter (volume 37, issue 1, pp. 3–9), published by The Cycad Society, carried three articles on the species: by J.L. Haynes on its nomenclature, morphology, phylogeny, distribution, habitat and conservation status, by G. Sparkman on growing it in southern California, and by G. van Deventer on a visit to its habitat (references listed by The World List of Cycads, which dates Haynes’s article 2004).

Common names

PlantZAfrica gives Kei cycad in English, after the Kei River, keibroodboom in Afrikaans, and umguza and umphanga in Xhosa; Species+ gives Kei cycad. Jungle Music also uses the name. No other English name is attested in a reliable source.

In the wild

Encephalartos princeps is endemic to the Eastern Cape, South Africa. Dyer (1965) places it on the dolerite cliffs and outcrops of the Kei basin, in the former districts of Queenstown, Cathcart, Komga, Tsomo and Butterworth; the original description also cites a specimen from King William’s Town district, on the Kabousie. The exact extent of the range towards the upper Kei and its mouth was not known in 1965; a record from Mqanduli, in the former Transkei, was based on a cultivated plant and remained to be confirmed. A photograph by Dyer shows, on the west bank of the Great Kei below the railway bridge, a clump whose trunks may all arise from the same rootstock.

PlantZAfrica describes riverine thicket, among rocks, and dolerite cliffs, with 420 to 520 mm of rain a year, hot summers and cool winters. Male and female cones give off strong smells early in the morning or in the evening, which attract weevils; moving from one sex to the other, the weevils carry the pollen. The fleshy seed coat attracts birds, rodents and bats, which disperse the seeds.

Conservation status and regulation

Encephalartos princeps is assessed as Vulnerable (VU) on the IUCN Red List under criteria A4acd (a population reduction, observed and projected, linked to habitat decline and collecting) and B1ab(iii,v) (a small range, with a decline in habitat quality and in the number of mature plants). The assessment, by J.D. Bösenberg, is dated 26 May 2020 and was published in 2022 (The World List of Cycads, GBIF, Crossref). The Red List of South African Plants already listed it as Vulnerable in 2009 (Raimondo et al., cited by PlantZAfrica).

The IUCN action plan for cycads (Donaldson, 2003) classed it as Vulnerable (criteria A4acd and C1), with 3,500 to 5,000 plants, a moderate decline, overcollecting and habitat destruction as threats, a moderate reduction in habitat and no known population in a protected area; it was already Vulnerable in 1997. The same document mentions the thickets of invasive Lantana camara that are spreading over the farmland of the Eastern Cape where the species grows. South Africa’s CITES Scientific Authority (SANBI) has published no non-detriment finding for it.

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; positive opinion of the EU Scientific Review Group of 20 June 2011 on artificially propagated plants from South Africa, limited to plants whose caudex does not exceed 15 cm in diameter (this followed a negative genus-wide opinion of December 2010, lifted in March 2011); a new consultation covering the whole genus has been open since 16 September 2026.

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 princeps

PlantZAfrica presents Encephalartos princeps as a handsome blue cycad that likes full sun and tolerates any type of soil, provided it is well drained and aerated, with moderate watering; its growth is rather slow. It suits a specimen position or group planting. Young plants are raised in shade for their first years, then planted out at three to five years old.

Outdoor and in-ground cultivation

In southern California, Jungle Music recommends sun on the coast and inland, partial sun or filtered light in desert areas, and a quick-draining soil that never stays too wet; in a more tropical, regularly irrigated garden it advises amending the soil and planting on a mound, and it considers the species suited to both tropical and arid gardens. In Europe, a grower near Nantes (Loire-Atlantique, western France) planted one in the ground in spring 2010, with an 8 cm caudex, dug it up in September 2011 because it was not getting enough sun, and replanted it in March 2012 in a very free-draining mix (Fous de palmiers forum); he noted, quoting American forums, that the species puts out its new leaves fairly early in the season. At Concarneau (Brittany), another grower planted one in the ground in 2011. On the same forum, a grower on the Côte Bleue (Bouches-du-Rhône, south-east France) considered in February 2010 that it absolutely needs a dry winter and doubted its success on the Atlantic coast.

Container cultivation

Its slow growth makes it suitable for a pot for many years, in a very free-draining mix and full sun. In Ravenna (Emilia-Romagna, Italy), a grower on the Tropicamente forum has kept a small plant bought in October 2009 in a pot, alongside the other cycads of his collection; in July 2013 it had produced the longest new leaf of all his species. In cool, wet climates, a container makes it possible to keep the plant dry and frost-free in winter.

In cultivation in the UK, US and Australia

BGCI PlantSearch lists 35 institutions holding the species. In the United Kingdom, the Cambridge University Botanic Garden lists an accession of 2018 in its online catalogue, and Kew declares the species. In the United States, the Montgomery Botanical Center (Coral Gables, Florida) lists two accessions, of 1977 and 2018; BGCI also lists Fairchild, the Huntington, Lotusland, the Los Angeles County Arboretum, Descanso Gardens, the Gardens of Golden Gate Park, the University of California Botanical Garden at Berkeley, the San Diego Botanic Garden, the San Diego Zoo and its Safari Park, SeaWorld San Diego, the Missouri Botanical Garden, Naples Botanical Garden and three Hawaiian gardens. In Australia, the Royal Botanic Garden Sydney lists it in its online catalogue and the Botanic Garden of Adelaide declares it. A BGCI listing records a declaration by the garden, not a living plant on display today. Jungle Music describes the species as rare and difficult to obtain, with seed very hard to get, and more expensive than most green cycads; it only sometimes has larger plants.

Propagation

PlantZAfrica describes a detailed protocol. Seeds are collected and completely cleaned of their flesh, which may contain germination inhibitors and encourage fungi (wear gloves, as it is poisonous), then stored for at least six months in a paper bag at 10 to 15 °C (50 to 59 °F), while the embryo completes its development. Before sowing, soak them for a few days, changing the water daily: viable seeds sink, the others float. Lay them half buried, on their side, in washed sand or a seed compost at 28 °C (82.4 °F), keeping the medium moist but not wet. Transplant them when the root is 1 to 2 cm long, or after one or two leaves, into narrow, tall bags (about 12 by 24 cm), since the taproot is long; mist daily at first, then water once a week after a month. Suckers are removed with a clean, sharp knife or spade; the wound is treated with fungicide and dried for a week before planting. Seeds, plants and suckers are all covered by CITES Appendix I.

Pests and diseases

PlantZAfrica mentions scale insects, which suck the sap of the leaves and are treated with repeated applications of horticultural oil, and beetles that attack the young leaves as they form, against which it recommends a contact or systemic insecticide. In cool, wet climates the main risk remains root rot in cold, waterlogged soil.

Cold hardiness

PlantZAfrica describes the species as frost- and drought-resistant. Dated reports are few and mostly concern young plants; as with all Encephalartos, survivals in cold areas often concern young plants whose caudex is still small or underground, protected by the thermal inertia of the soil and sometimes by snow or a cover; adult plants with an aerial trunk do not benefit from this protection.

Mediterranean and European experience

  • Loire-Atlantique (western France): near Nantes, a plant in the ground since spring 2010, protected by a cloche, was intact in December 2010 after a month of almost daily frost with several days at −5 to −6 °C (23 to 21.2 °F); its grower reported in March 2012 that it had withstood −6 to −7 °C (21.2 to 19.4 °F) the previous winter without any damage (Fous de palmiers forum). These are the garden’s temperatures, not readings under the cloche. The plant had been dug up before the cold spell of February 2012.
  • Brittany (north-west France): at Concarneau, a plant set out in the ground in 2011 had, in April 2012, a “very healthy” caudex after a winter with a minimum of −5 °C (23 °F); its leaves, formed before planting, had been shredded by the December storms (Fous de palmiers forum).
  • Italy: in Ravenna, a young plant in a pot, bought in October 2009, was the plant that best withstood −7 °C (19.4 °F) in a cold glasshouse in the winter of 2009–2010: it showed no marks in January 2010, whereas all the leaves of the same grower’s Encephalartos lehmannii were burnt (Tropicamente forum).

These reports, from Atlantic and northern Italian climates, are relevant to readers in comparable climates, such as the milder parts of southern England, or coastal California and southern Australia for the Mediterranean experience; they concern young, protected or potted plants over one or two winters.

United Kingdom, United States and Australia

  • United States: at the Juniper Level Botanic Garden in North Carolina, Encephalartos princeps did not survive, in the ground and unprotected, the winter of 2013–2014, with minimums of −13 to −16 °C (9 to 4 °F, the values given by the garden) depending on the location; neither did Encephalartos lehmannii or Encephalartos longifolius.
  • Japan, for comparison: in the Kansai plain, during the cold spell of the winter of 2020–2021 (three days with daily means of −2 to −3 °C, 28.4 to 26.6 °F), only the new leaves produced in late autumn, not yet hardened, were partly destroyed; the rest of the plant was unharmed (Japanese grower’s blog, March 2021).
  • United Kingdom and Australia: no hardiness data have been published for the species; the British gardens that hold it grow it under glass or do not say.

No USDA zone is documented for Encephalartos princeps in a reliable source.

Toxicity and precautions

Like other cycads, Encephalartos princeps contains toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived; these substances affect the liver and the nervous system, and the seeds are the most dangerous part. PlantZAfrica points out that most parts of cycads are poisonous and that the poison acts slowly. Wear gloves to handle seeds, 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

PlantZAfrica recalls, for cycads in general, that local people once made a flour from the pith of the trunks; no use specific to Encephalartos princeps is described. Today the species is grown as an ornamental.

Frequently asked questions

Is Encephalartos princeps frost-hardy?

To some degree, when young and protected. Near Nantes, in western France, a young plant in the ground under a cloche came through −5 to −7 °C (23 to 19.4 °F) without damage in the winter of 2010–2011, and in Ravenna a potted plant withstood −7 °C in a cold glasshouse; but a plant in the ground died at −13 to −16 °C (9 to 4 °F) in North Carolina. A very free-draining soil, dry in winter, and protection during cold spells remain necessary.

How can it be told from Encephalartos lehmannii?

By the leaflets and habit: Encephalartos princeps has more crowded leaflets, overlapping in the upper part of the leaf, a small, hidden pulvinus, taller trunks and clustered cones with warty scales; Encephalartos lehmannii has more widely spaced leaflets, a large, visible pulvinus with a reddish-brown collar, shorter trunks and solitary cones.

Why is it called princeps?

Because Dyer thought it had a longer history and a more stately habit than its near relatives: princeps means “first” in Latin.

Can it be grown in a pot?

Yes, at least in its early years, since it grows slowly: choose a very free-draining mix and full sun. In Ravenna, a young plant in a pot kept in a cold glasshouse came through a winter at −7 °C (19.4 °F) well.

How do you germinate its seeds?

By letting them mature for at least six months after harvest, dry and cool, then soaking them and sowing at 28 °C (82.4 °F), following the PlantZAfrica protocol (see Propagation).

Is it poisonous?

Yes, especially its seeds, as in all cycads.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Dyer, R.A. (1965). New species and notes on type specimens of South African Encephalartos. Journal of South African Botany 31(2): 111–121, plates 19–20. [Original description of Encephalartos princeps, pp. 111–112: diagnosis, dimensions, type, distribution, differences from Encephalartos lehmannii, etymology; Internet Archive scan.]
  • Dyer, R.A. (1965). The cycads of southern Africa. Bothalia 8: 405–515. [Key, description, range, soils, distinction from Encephalartos lehmannii, Encephalartos trispinosus and Encephalartos friderici-guilielmi.]
  • Hutchinson, J. & Rattray, G. (1933). Cycadaceae. Flora Capensis 5(2), supplement. [Queenstown specimens placed under Encephalartos lehmannii; cited by Dyer (1965).]
  • Henderson, M.R. (1945). Materials for a revision of the South African species of Encephalartos. Journal of South African Botany 11: 3–65. [“Form D” of Encephalartos lehmannii; cited by Dyer (1965).]
  • Kemp, M. (1990). Focus on Encephalartos princeps. Encephalartos 24: 3–7. [Journal of the Cycad Society of South Africa; cited by The World List of Cycads.]
  • Donaldson, J.S. (ed.) (2003). Cycads. Status Survey and Conservation Action Plan. IUCN/SSC Cycad Specialist Group, Gland and Cambridge. [Table of statuses, invasive plants.]
  • The Cycad Newsletter 37(1) (2014): 3–9, articles by J.L. Haynes (nomenclature, morphology, phylogeny, distribution, habitat and conservation status), G. Sparkman (growing in southern California) and G. van Deventer (visit to the habitat). [Cited by The World List of Cycads.]
  • Raimondo, D. et al. (eds) (2009). Red List of South African Plants 2009. Strelitzia 25. SANBI, Pretoria. [National status, cited by PlantZAfrica.]
  • Bösenberg, J.D. (2022). Encephalartos princeps. The IUCN Red List of Threatened Species 2022: e.T41922A51045400. [Current assessment, cited by The World List of Cycads and Crossref.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. [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.]