In the Palm House at the Royal Botanic Gardens, Kew, a cycad stands that has been in continuous cultivation since before the French Revolution. Encephalartos altensteinii was brought to Kew from the Eastern Cape of South Africa in 1775 — making it the oldest pot plant in the world for which continuous documentation exists. This Encephalartos has survived two and a half centuries of British winters, two world wars, the construction and reconstruction of the glasshouse around it, and the attention of millions of visitors. It is a living monument to the extraordinary longevity of cycads and to the tenacity of institutional horticulture.
Taxonomy and nomenclature
Encephalartos altensteinii Lehm. was described by Lehmann in 1834, based on material from the Eastern Cape. The epithet honours Baron Karl vom Stein zum Altenstein (1770–1840), a Prussian statesman and patron of science who served as Minister of Culture. The original Kew specimen predates the formal scientific description by nearly sixty years — the plant was growing in a pot at Kew before it had a Latin name.
Encephalartos altensteinii is one of the larger, more robust species in the genus, belonging to a group of green-leaved, arborescent Eastern Cape species that includes Encephalartos longifolius and Encephalartos natalensis.
Common names: Altenstein’s cycad, Eastern Cape giant cycad (English); broodboom (Afrikaans — literally “bread tree”, from the historical use of the starchy trunk pith as food).
Morphological description
Habit and caudex: Encephalartos altensteinii is one of the largest species in the genus. The trunk is erect, columnar, typically reaching 3–5 m in height (occasionally to 7 m), and 30–45 cm in diameter. The trunk is stout and straight, clothed in persistent leaf bases. Branching is uncommon but occurs occasionally. The crown is large and spreading, bearing 20–40 fronds — a commanding presence in any landscape.
Leaves: Fronds are 1.5–2.5 m long, pinnate, with a graceful arching habit. Leaflets are oblong-lanceolate, 12–18 cm long and 2–3 cm wide, with smooth margins (no spines or lobes — a relief after the armed species) or occasionally with 1–2 small teeth. The colour is a rich, glossy dark green. New fronds emerge pale green to yellowish. The overall frond form is elegant and palm-like — less architectural than the blue species, but with a lush tropical quality that makes mature specimens imposing landscape plants.
Reproductive structures: Male cones are cylindrical, 30–50 cm long, yellowish-green. Female cones are very large — ovoid, 40–60 cm long, among the biggest in the genus — yellowish-green, producing bright red-orange seeds. A mature female bearing a massive cone above the crown of dark green fronds is a truly impressive sight.
Distribution and natural habitat
Encephalartos altensteinii is endemic to the Eastern Cape Province of South Africa, with a distribution extending from the Bathurst district eastward to East London and the Transkei coast. It occurs at low to moderate elevations (sea level to 600 m), in coastal and valley bushveld — typically in thicket vegetation on south-facing or shaded slopes where soil moisture is somewhat higher than the surrounding landscape.
The climate is subtropical to warm-temperate, with annual rainfall of 500–900 mm distributed throughout the year. Summers are warm (25–30 °C), winters are mild (10–18 °C daytime, 2–8 °C nights). Light frost occurs at inland sites but is infrequent and brief on the coast. The Eastern Cape coastal climate is significantly milder and wetter than the semi-arid Karoo margin habitat of Encephalartos lehmannii.
Conservation status
Encephalartos altensteinii is listed as Vulnerable (VU) on the IUCN Red List. The species has a moderate range and a sizeable total population, but habitat destruction, illegal collection of large specimens (which command high prices in the black-market cycad trade), and poor recruitment in degraded habitats are ongoing concerns. It is protected under CITES Appendix I and South African national legislation.
Cultivation guide
Difficulty: 2/5 — easy and vigorous.
Light: Full sun to partial shade. More shade-tolerant than the blue species — in the wild, it grows in thicket vegetation with some canopy cover. In cultivation, it performs well in both open sun and dappled shade.
Soil: Well-drained, moderately fertile. Less demanding about mineral content than the blue species — a standard well-drained mix with moderate organic matter works well. Slightly acidic to neutral pH (5.5–7.0).
Watering: Regular. More moisture-demanding than the Karoo species. Water generously in summer, moderately in winter. Established in-ground plants in Mediterranean climates are reasonably drought-tolerant but perform best with regular irrigation.
Cold hardiness: Moderate. The coastal Eastern Cape habitat is mostly frost-free, but inland populations experience occasional light frost (−2 to −4 °C). In cultivation, reliable in USDA Zone 9b (−1 to −4 °C). Zone 9a is possible with shelter and good drainage but frond damage is likely. Less cold-tolerant than Encephalartos horridus or Encephalartos lehmannii.
Container culture: Good when young. The vigorous growth rate and eventual size (trunk to 5+ m) mean that container culture is a juvenile-phase solution. Young plants make handsome specimens in large pots for several years before they outgrow their containers.
Propagation
Seed: Standard Encephalartos protocol. Remove the sarcotesta, soak, plant in free-draining medium at 25–30 °C. Germination: 3–12 months. Seedlings are relatively vigorous for an Encephalartos.
Offsets: Produced occasionally from the trunk base. Detach and root in warm conditions.
Authority websites
POWO — Plants of the World Online: https://powo.science.kew.org/…
IUCN Red List: https://www.iucnredlist.org/species/41881/10582570
PlantZAfrica (SANBI): http://pza.sanbi.org/encephalartos-altensteinii
Royal Botanic Gardens Kew — The oldest pot plant: https://www.kew.org
World List of Cycads: https://cycadlist.org
Bibliography
Lehmann, J.G.C. (1834). Novarum et minus cognitarum stirpium pugillus sextus. Hamburg. [Original description]
Goode, D. (2001). Cycads of Africa. Struik Publishers, Cape Town. 352 pp.
Jones, D.L. (2002). Cycads of the World. 2nd ed. Smithsonian Institution Press, Washington. 456 pp.
Desmond, R. (1995). Kew: The History of the Royal Botanic Gardens. Harvill Press, London.