Discorea elephantipes

Most species in the genus Dioscorea are tropical yams grown for an underground, edible tuber. A small handful of South African species took the opposite evolutionary route, pushing their water-storing organ above ground instead of hiding it below. Dioscorea elephantipes is by far the best known and most widely grown of these: a woody caudex sheathed in corky bark that cracks with age into polygonal plates, giving the plant the look of a tortoise shell or, as its name suggests, the fissured skin of an elephant’s foot. Native to the arid interior of the South African Cape, this slow-growing, dioecious species is one of the most sought-after caudiciform plants among collectors worldwide, and a well-grown specimen can remain in cultivation for many decades.

Identification

The caudex is the immediate diagnostic feature: hemispherical to flattened-domed, greyish-brown, its surface splitting with age into angular plates of four to seven sides separated by deep fissures. In the wild, exceptional specimens can approach a metre in height above ground and roughly three metres in circumference, with an estimated weight of up to 365 kg — figures that remain theoretical for cultivated plants, which never come close to matching centuries-old wild populations.

Each growing season, one or more twining stems emerge from the crown of the caudex, spiralling to the left and bearing alternate, heart-shaped (cordate) leaves that are notably small, generally under 2.5 cm — a useful character for separating it from its Mexican look-alike (see Look-alikes, below). The inconspicuous, greenish-yellow flowers, sometimes dark-spotted, appear in winter; being dioecious, male inflorescences form upright, spiny racemes while female ones hang as drooping, spinescent spikes. The fruit is a roughly 2.5 cm capsule releasing winged seeds.

Look-alikes

The species most often confused with Dioscorea elephantipes is Dioscorea mexicana (synonym Dioscorea macrostachya), native not to South Africa but to Mexico and Central America as far as Panama. A long-running exotic-plant forum thread has documented this recurring confusion since 2009, with side-by-side photographs of both species and their leaves. Two further South African relatives in the same informal Testudinaria group are worth naming without being genuine sources of confusion to a trained eye: Dioscorea sylvatica, more variable and faster-growing, some forms of which also develop a plated caudex; and the critically rare Dioscorea strydomiana from Mpumalanga (fewer than 250 known mature individuals), whose bark recalls Dioscorea elephantipes even though its habit, leaves, and flowers differ clearly on closer inspection.

Criterion	Dioscorea elephantipes	Dioscorea mexicana
Geographic origin	South Africa (Cape provinces)	Mexico to Panama
Caudex shape	Hemispherical, deep and irregular fissures	Flatter, dome-shaped, regular polygonal plates
Leaf size	Small, generally under 2.5 cm	Distinctly larger, 7–10 cm
Annual vine vigour	Moderate, a few metres	Very vigorous, up to 9 m
Native growing season	Winter–spring	Mainly summer, faster growth
Documented cultivated hardiness	More cold-tolerant, grown outdoors year-round in mild coastal Mediterranean-type climates	Generally requires winter shelter in the same climates

Taxonomy

Dioscorea elephantipes (L’Hér.) Engl. was published by Engler and Drude in 1908 (Die Vegetation der Erde 9(III,2): 367), based on the basionym Tamus elephantipes L’Héritier (1789). It belongs to the family Dioscoreaceae, order Dioscoreales, and is the currently accepted name according to Plants of the World Online (Kew). Homotypic synonyms include Testudinaria elephantipes (L’Hér.) Burch. (1824), a name long used in horticulture and still frequently seen in collector circles, as well as Rhizemys elephantipes (L’Hér.) Raf. (1838). Two later combinations, Dioscorea elephantopus Spreng. and Dioscorea testudinaria R.Knuth, are treated as illegitimate names.

Common names include Elephant’s Foot and Turtle Shell, alongside the Afrikaans Olifantsvoet and Hotnotsbrood. The English name Hottentot Bread, though still widely used, derives from a colonial-era term now considered derogatory toward the people it referred to; the currently preferred designation is Khoikhoi.

In the Wild: Habitat, Range and Climate

Dioscorea elephantipes is endemic to South Africa’s Cape provinces. Its range extends from around Springbok in the Northern Cape, south through the Clanwilliam and Cederberg area of the Western Cape, and east through the Graaff-Reinet, Willowmore and Uniondale districts of the Eastern Cape, as far as the outskirts of Grahamstown. The species grows between 150 and 1,200 m elevation on dry, rocky slopes derived from quartzite or shale, within thorny succulent karroid thicket, often sheltered under protective shrubs such as Carissa haematocarpa.

The climate across this range is semi-arid to steppe (Köppen BSk), with recorded temperature extremes running from around -4°C in winter to above 40°C in summer. Annual rainfall is low and varies by locality, broadly in the 150–350 mm range: it is markedly winter-dominant in the western part of the range around Clanwilliam, but becomes more evenly spread, with autumn and spring peaks, further east and inland in the Karoo interior around Graaff-Reinet. Light winter frost is common across much of the range — the corresponding South African horticultural zone is described as “winter-rainfall Karoo, light frost.” Snow is rare but not entirely absent at the higher, more continental eastern margins of the range in severe winters, though it is not a defining feature of the species’ core habitat.

Conservation

The most recent Red List of South African Plants assessment (SANBI, 2022) places the species as Least Concern, with an extent of occurrence of 266,005 km² and an area of occupancy of 340 km² across more than thirty recorded locations. The population trend is nonetheless considered to be decreasing, with under 10% of the population lost to date to illegal collection for the specialist horticultural and traditional medicine trades, and to trampling and grazing by Angora goats. The species is additionally listed on CITES Appendix II, which regulates international trade.

Cold Hardiness

Habitat data point to occasional tolerance down to around -4°C in well-corked, mature caudices. Even so, a plant’s resistance to abiotic stress — temperature, sun exposure, humidity, substrate, wind — is never governed by a single trait fixed by the species alone, but by the combination of many factors specific to each growing situation, which is why cultivation reports vary so widely.

A 2009 PalmTalk forum thread from a grower in Southern California offers a directly useful comparison: Dioscorea elephantipes proved noticeably hardier than Dioscorea mexicana, growing outdoors year-round on the coast without protection while the Mexican species had to be brought indoors each winter — consistent with habitat data showing that Dioscorea elephantipes regularly experiences light frost that its Mexican counterpart does not encounter in its native range. On the CactiGuide forum, a grower in Rome documented in 2017 carrying a young plant through a winter with ambient temperatures between 7 and 18°C, with the community advising a reduction — not a full stop — in watering as long as the foliage persisted, judging by leaf condition rather than the calendar. A separate, long-running CactiGuide thread from the Los Angeles area (2016–2020) documents repeated caudex rot linked to directly misting the tuber, a cautionary data point independent of climate zone.

The USDA hardiness zone figures commonly quoted by commercial sites (typically 9b–11b) should be treated with caution: they describe survival thresholds for an exposed caudex, not the conditions needed for vigorous, long-term growth. This article prioritises habitat data and documented grower reports over commercial hardiness claims, which tend to run systematically optimistic.

Cultivation

Outdoor / in-ground cultivation

Where winters stay frost-free or only lightly frosted, Dioscorea elephantipes can be grown in the open ground on a raised, sharply draining bed, with the caudex left largely exposed as it would be in habitat. Full sun to bright light on both caudex and vines is associated with markedly stronger growth in documented grower reports, in contrast to the stagnation observed in partially shaded plants. Winter protection — a dry mulch, a frost cloth, or simply siting the plant against a warm, sheltered wall — is worth considering wherever temperatures regularly approach freezing, since young or container-raised caudices with thinner bark are considerably more vulnerable than large, well-corked habitat specimens.

Container cultivation

Potted specimens need a very free-draining, mineral-dominant mix — crushed pumice or lava rock, coarse sand, and a modest fraction of loam or compost are generally sufficient — in a pot that is wide and shallow relative to the caudex, upsized gradually as the caudex grows rather than buried deeper into a taller pot. Only the root-bearing base of the caudex should sit in contact with the substrate. Watering follows the growth cycle: regular during active growth (autumn through spring under a Mediterranean-type climate), letting the substrate dry between waterings, then drastically reduced or stopped once the vines die back at the onset of summer dormancy — this single decision matters more than any other for the plant’s longevity, since overwatering during dormancy remains the leading cause of caudex rot. Several growers caution against wetting the caudex itself directly, since standing moisture in the fissures may allow pathogens in, though the point remains informally debated among practitioners. A light, diluted cactus-and-succulent fertiliser can be applied during active growth only, never as the plant approaches dormancy.

Propagation

Propagation is almost exclusively by seed: the entire visible above-ground body of the plant is a single caudex, so there is no viable cutting or division method. Fresh seed germinates best in a warm, moist, well-drained medium. Growers report germination can be erratic, with entire batches occasionally failing to show at all, suggesting that sowing timing matters more to success rates than is commonly assumed.

Caudex growth is extremely slow: roughly 10 mm in diameter after the first year, and only about 120 mm after five years, according to figures from South Africa’s national botanical institute. A caudex with genuine ornamental presence therefore represents, at minimum, one to two decades of patient cultivation — worth bearing in mind before choosing seed over an already-established plant.

Pests and diseases

Mealybugs, which readily shelter in the caudex fissures, along with red spider mite and thrips, are among the most frequently reported pests, particularly under enclosed glasshouse conditions where warmth and stagnant humidity favour their spread; one major UK botanical collection notes deliberately keeping its growing area on the cool side specifically to limit these infestations. Caudex rot, most often triggered by excess moisture during dormancy or by standing water in the surface fissures, remains the principal cultivation risk for this species.

Ornamental interest and traditional uses

Dioscorea elephantipes is one of the most sought-after caudiciform plants in cultivation worldwide, prized for its sculptural, reptilian-plated caudex. On the ethnobotanical side, the starch-rich tuber was historically baked and eaten by the Khoikhoi people of the Cape as a famine food — the origin of the common name Hottentot Bread, a term now considered outdated and derogatory when applied directly to the people concerned.

More broadly, several species within the genus Dioscorea — though not primarily Dioscorea elephantipes itself — are commercially important sources of diosgenin, a steroidal saponin used as a precursor in the industrial synthesis of cortisone and oral contraceptives. That pharmaceutical value has historically driven overharvesting in a number of related South African species, a pressure SANBI also cites, alongside illegal horticultural collection, among the current threats to wild Dioscorea elephantipes populations — one more reason to source only nursery-grown, seed-propagated plants.

FAQ

Does the growing calendar need to be reversed because the plant is from the Southern Hemisphere? No. The Cape and Mediterranean-type climates both follow a hot-dry-summer / cool-wet-winter pattern; growers across Mediterranean Europe and coastal California report the plant tracking local seasonal cues rather than the Southern Hemisphere calendar.

Can the plant be propagated from a cutting of the caudex? No — seed is the only viable propagation method; there is no cutting or division route for this species.

Should the caudex itself be watered along with the rest of the substrate? Caution is warranted: several growers report rot linked to standing moisture in the caudex fissures, though the practice remains informally debated.

How long does it take to grow a caudex of real size? At least one to two decades: growth is around 10 mm in diameter in the first year and only about 120 mm after five years.

Bibliography

Von Teichman und Logischen, I., Van Der Schijff, H. P. & Robbertse, P. J. (1975). The genus Dioscorea L. in South Africa. Boissiera 24: 215-224. [A historical taxonomic reference cited by POWO as an authority for the genus in southern Africa; useful for situating Dioscorea elephantipes within its genus.]

Engler, H. G. A. & Drude, C. G. O. (1908). Die Vegetation der Erde 9(III,2): 367. [Original publication of the accepted name Dioscorea elephantipes.]

Wilkin, P. (2017). Dioscorea elephantipes. The IUCN Red List of Threatened Species. [The global reference assessment underlying the more recent SANBI national assessment cited in this article.]

Victor, J. E. & Mhlongo, A. P. (2022). Dioscorea elephantipes (L’Hér.) Engl. National Assessment. Red List of South African Plants version 2024.1, SANBI. [The most recent national assessment, used here for current conservation status and documented threats.]