Aloidendron dichotomum is perhaps the most photographed and most iconic member of the genus Aloe and its allies — a slow-growing succulent tree whose forking silhouette against a Namibian sunset has become a symbol of the southern African desert. Long classified within the genus Aloe as Aloe dichotoma, molecular phylogenetic evidence placed it in the genus Aloidendron (the “tree aloes”), a lineage of arborescent succulents that diverged early from the main alooid radiation. The quiver tree can reach nine metres in height and live over eighty years, forming dense rounded crowns of smooth, forking branches tipped with rosettes of blue-green leaves. Its bright yellow winter flowers attract sunbirds and baboons. Throughout much of its range, the species is in decline due to climate change. This article covers the taxonomy, ecology, morphology, cultivation, conservation and cold hardiness of this extraordinary tree.
Taxonomy and botanical history
Aloidendron is a genus of six accepted species of arborescent (tree-forming) succulents in the family Asphodelaceae (subfamily Asphodeloideae). The genus was formally established by Grace, Klopper, Smith et al. in 2013 (Phytotaxa 76: 7–14), based on molecular evidence showing that the tree aloes form a monophyletic clade that diverged early within the alooid radiation. The genus name combines Aloe with the Greek dendron (“tree”). Manning et al. (2014) confirmed the circumscription in their comprehensive revision of Alooideae (Systematic Botany 39(1): 55–74).
Aloidendron dichotomum was first described by the Scottish botanist Francis Masson, one of the first professional plant collectors sent from Kew to the Cape. The specific epithet dichotomum comes from the Greek dikhotomia (“a cutting in two”), referring to the characteristic pattern of dichotomous branching: every branch fork splits into exactly two equal limbs, producing the densely rounded, symmetrical crown that is the species’ most recognisable feature.
The earliest documented record of the species predates Masson: it appears in the diary of Simon van der Stel, Governor of the Cape, who encountered the tree during his 1685 expedition to the Copper Mountains of Namaqualand. Van der Stel recorded it as “Aloe arborescens; its trunk is sometimes 12 feet high, and it has a beautiful, clear and copious sap.”
Nomenclatural synonyms (according to POWO): Aloe dichotoma Masson — basionym. Rhipidodendrum dichotomum (Masson) Willd.
Common names: “quiver tree” in English (from the San people’s practice of hollowing out the branches to make quivers for their arrows); “kokerboom” in Afrikaans (same meaning); “choje” in the San language.
Conservation status: Aloidendron dichotomum is listed as Vulnerable (VU) on the IUCN Red List and on CITES Appendix II. Field surveys have confirmed modelled range declines driven by climate change. The species is considered a flagship for climate-change research in the southern African flora.
The three sympatric tree aloes
Three separate Aloidendron species inhabit the same arid landscapes of the Richtersveld and the Namib Desert around the South Africa–Namibia border: Aloidendron dichotomum, Aloidendron pillansii (L.Guthrie) Klopper & Gideon F.Sm. (the giant quiver tree, critically endangered), and Aloidendron ramosissimum (Pillans) Klopper & Gideon F.Sm. (the maiden’s quiver tree, considerably smaller, rarely exceeding 2 m). They can be distinguished as follows: in Aloidendron pillansii, the inflorescences hang from below the lowest leaves rather than growing erect; Aloidendron ramosissimum is much smaller and more shrub-like.
Ecology
Native range
Aloidendron dichotomum is indigenous to the Northern Cape Province of South Africa and southern to central Namibia. According to POWO and SANBI, its range extends from near Nieuwoudtville in the Northern Cape northward into Namibia as far as the Brandberg, and eastward to the Upington and Kenhardt area. World of Succulents extends the eastern limit to Olifantsfontein in Gauteng Province, though this may represent cultivated or naturalised populations.
Habitats
The quiver tree grows on rocky slopes, dolerite outcrops (called “ysterklip” — iron rock — in Afrikaans), and sandy flats in the arid zones generally known as Namaqualand and Bushmanland. It is a conspicuous component of the Succulent Karoo and Nama-Karoo biomes. The dark rock formations on which it commonly grows absorb heat during the day and radiate it back at night, creating a microclimate that may help protect against frost. The extensive, shallow root system spreads over a wide area to capture the sparse rainfall.
Two famous concentrations of the species exist: the Quiver Tree Forest (Kokerboomwoud) approximately 14 km north of Keetmanshoop in Namibia, a national monument, and the Gannabos quiver tree forest in the Northern Cape of South Africa.
Climate in habitat
The quiver tree inhabits one of the most extreme climates tolerated by any alooid. The environment is true desert or semi-desert, with winter rainfall.
Winter (May–August): cool to cold nights. Frost is regular in the interior. Minimum temperatures of −5 to −8 °C (23 to 18 °F) occur on exposed sites, though the thermal mass of the rocky substrate on which the trees grow moderates the microclimate. Daytime temperatures are mild (18–25 °C / 64–77 °F). Sparse winter rainfall provides the main water supply.
Summer (November–February): extremely hot. Average summer temperatures reach 38 °C (100 °F) in many parts of the range, with maxima exceeding 45 °C (113 °F). Rainfall is essentially absent in the winter-rainfall zone. The reflective whitish powder on the branches and the blue-green (glaucous) leaf colour are adaptations to reduce heat absorption under this intense solar radiation.
Annual rainfall is very low: 50 to 200 mm (2 to 8 in), falling mainly as light winter events.
Description
Growth habit
Aloidendron dichotomum is a succulent tree with a stout, unbranched trunk for the lower half to two-thirds of its height, topped by a dense, rounded crown of smooth, repeatedly forking branches. Mature trees typically reach 5 to 7 m (16 to 23 ft) in height, with exceptional specimens reaching 9 m (30 ft). The trunk can reach 1 m (3 ft) in diameter at the base. Trees may live over 80 years — some estimates suggest considerably longer, though precise aging is difficult in the absence of growth rings.
Growth is extremely slow. The species typically does not flower until it is 20 to 30 years old.
Trunk and bark
The trunk bark forms beautiful golden-brown scales, the edges of which are razor-sharp — an effective anti-herbivore defence. SANBI specifically warns that the bark edges are dangerously sharp. The upper branches are covered with a thin layer of whitish powder (pruinose coating) that reflects solar radiation and reduces water loss — an adaptation to the extreme heat of the Namib fringe.
The trunk interior is fibrous and spongy, not woody in the conventional sense. This tissue has insulating and evaporative-cooling properties. Large hollow trunks of dead trees have traditionally been used as natural refrigerators by indigenous peoples: water, meat and vegetables stored inside are cooled by the evaporative effect of air passing through the fibrous tissue.
Leaves
The leaves are borne in dense terminal rosettes at the tips of the uppermost branches. They are succulent, blue-green (glaucous), approximately 30 cm (12 in) long and narrow, with small brown teeth along the margins. In juvenile plants, the leaves are arranged in vertical rows rather than in rosettes — a juvenile character that is progressively lost as the plant develops its branching architecture.
Inflorescence and flowers
The inflorescence is a branched panicle approximately 30 cm (12 in) tall, bearing bright yellow, tubular flowers about 3 cm (1.2 in) long, with orange stamens protruding from the mouth. The racemes are erect and borne at the tops of the branches, within or just above the leaf rosettes.
Flowering period
In the wild (Southern Hemisphere), Aloidendron dichotomum flowers in winter, from June to July. The copious nectar attracts sunbirds, bees, insects and even baboons — SANBI notes that baboons can strip a tree of its flowers in short order.
Ecological role
Being one of the only tree-sized plants in its arid habitat, Aloidendron dichotomum is a keystone species. The branches frequently host the enormous communal nests of sociable weavers (Philetairus socius), which can contain thousands of individual nests and weigh enough to break the branches. These nests provide shelter and breeding sites for the weavers and their predators (particularly Cape cobras and boomslangs). The tree is thus a critical structural element of the desert ecosystem.
Comparison with two related species
Aloidendron dichotomum vs Aloidendron pillansii (L.Guthrie) Klopper & Gideon F.Sm.
Aloidendron pillansii (the giant quiver tree, or bastard quiver tree) is the tallest species in the genus, reaching up to 10–15 m. It is listed as Critically Endangered.
Key differences:
Inflorescence position: in Aloidendron dichotomum, the inflorescences are erect and emerge from above or within the leaf rosettes. In Aloidendron pillansii, the inflorescences hang downward from below the lowest leaves — a unique character in the genus.
Leaf arrangement: the leaves of Aloidendron pillansii are more densely packed and the rosettes are less clearly defined than in Aloidendron dichotomum.
Conservation status: Aloidendron pillansii is Critically Endangered, with fewer than 200 mature individuals remaining. Aloidendron dichotomum is Vulnerable but far more numerous.
Aloidendron dichotomum vs Aloidendron ramosissimum (Pillans) Klopper & Gideon F.Sm.
Aloidendron ramosissimum (the maiden’s quiver tree) is the smallest tree aloe in the Richtersveld.
Key differences:
Size: Aloidendron ramosissimum rarely exceeds 2 m (6.5 ft) and is more shrub-like. Aloidendron dichotomum reaches 7–9 m.
Branching: Aloidendron ramosissimum branches more profusely from a lower point, giving a bushier, multi-stemmed appearance.
Distribution: Aloidendron ramosissimum has a very restricted range in the Richtersveld. Aloidendron dichotomum is far more widespread.
Optimal growing conditions
SANBI notes that Aloidendron dichotomum “features quite prominently in gardens all over South Africa and other countries with a similar climate,” but that “in wetter parts of South Africa such as the Western Cape, these plants are able to cope provided that the drainage is good enough to prevent rotting in the wet winters.” Wikipedia adds that the species is “relatively difficult to keep outside of its natural habitat.”
Light
Full sun. This is a desert tree that experiences some of the most intense solar radiation on Earth. Provide the sunniest position available. Inadequate light causes soft, etiolated growth and failure to develop the compact branching form.
Substrate
Extremely well-drained, coarse mineral sand. Wikipedia recommends “coarse mineral sand, preferably with some loam and bone meal to keep it active and growing.” A New Zealand grower on Dave’s Garden recommends a mix of one quarter cactus mix, one quarter coarse outdoor tub mix, and one half pumice. The substrate must dry out rapidly and completely between waterings. Standard potting mixes are too moisture-retentive.
Watering
Very sparingly — this is one of the driest-growing alooids. In cultivation, water primarily during the winter growing season (in its native rainfall pattern) and withhold almost entirely in summer. In Mediterranean climates where winter rain provides natural irrigation, additional watering may be unnecessary. Overwatering is the primary cause of death in cultivation. Root rot from stagnant moisture is fatal and often invisible until the trunk softens irreversibly.
Temperature
The species tolerates both extreme heat (over 40 °C / 104 °F in habitat) and moderate frost. See cold hardiness section below.
Growth rate
Extremely slow. From seed, expect years before the plant develops a recognisable trunk, and decades before it achieves the iconic branching silhouette. First flowering occurs at approximately 20 to 30 years of age. This slow growth, combined with conservation-driven rarity, makes mature specimens extremely expensive.
Propagation
Seed is the most reliable method. Sow on well-draining mineral substrate and keep barely moist at 20–25 °C (68–77 °F). Germination is usually reliable. Cuttings (truncheons) are possible but more difficult: they require thorough drying for several weeks in a shaded area before planting, to prevent rot at the cut surface.
USDA hardiness zones
Zones 9a to 11b (World of Succulents, Plant Lust). Foliage Factory lists zones 10–13, which is more conservative and may reflect the species’ sensitivity to wet cold. Kew grows it under glass with a minimum of 10 °C (50 °F).
Cold hardiness: documented evidence
The cold hardiness of Aloidendron dichotomum is often underestimated. The species experiences regular frost in its native habitat — the Karoo and Namaqualand interior have cold winter nights. However, the frost it experiences in habitat is always dry, on well-drained rocky substrate, with intense daytime warming.
Documented reports
SANBI (PlantZAfrica): describes the species as “an extremely tough tree” and notes successful cultivation in wetter parts of South Africa (Western Cape) “provided that the drainage is good enough.”
POWO (Kew): grows the species under glass with a minimum of 10 °C but acknowledges it “could tolerate a temperature slightly lower than this.” Notes it can be grown outdoors in a pot for summer in the United Kingdom.
Wikipedia: describes the species as “proof against frost” in habitat, but acknowledges difficulty in cultivation outside its native range.
Etsy vendor (specialist grower): “the quiver tree is proof against frost” in its natural rocky habitat.
World of Succulents: zones 9a to 11b, minimum −6.7 °C (20 °F).
Dave’s Garden (Phoenix, Arizona): a grower reports mixed luck, with four specimens in the ground, the tallest at five feet with one head. Another Arizona grower notes that roots can extend far and into irrigated beds, causing fatal rot.
Dave’s Garden (Coastal Otago, New Zealand, zone 9b): describes the species as “no more demanding than the other tree aloes” but warns against risking a zone 8 winter: “dichotomas can take a light frost especially if dry but dont risk a zone 8 winter or even a nasty zone 9 one.”
Succulent Guide: minimum zone 9a, 20–25 °F (−6.7 to −3.9 °C).
Summary of survival thresholds
| Condition | Estimated threshold | Sources |
|---|---|---|
| Dry rocky substrate, established tree, desert climate | −5 to −8 °C (23 to 18 °F) — routine in habitat | SANBI, Wikipedia (native climate data) |
| Dry well-drained soil, Mediterranean garden | −4 to −6 °C (25 to 21 °F) | World of Succulents, Dave’s Garden NZ |
| Moist or wet soil, maritime climate | 0 to −2 °C (32 to 28 °F) — high risk of fatal rot | Kew (10 °C minimum under glass) |
The practical message is clear: Aloidendron dichotomum is frost-tolerant in its native context of dry, rocky desert with extreme drainage and zero winter moisture around the roots. In any climate where winter rain is possible, the interaction of cold and wet is the primary killer. In Mediterranean gardens (USDA zone 9b and warmer), success depends entirely on achieving near-desert drainage conditions.
Practical recommendations
In USDA zone 10a and warmer with dry winters, Aloidendron dichotomum can be grown in the ground in full sun with very well-drained substrate. Ensure the root zone is elevated or on a slope to prevent any water accumulation.
In USDA zone 9b, container culture is safer. Use a deep terracotta pot (not plastic, which retains moisture) with a very mineral substrate. Move under cover during prolonged wet periods in winter. A position against a south-facing wall provides thermal mass and rain shadow.
In USDA zone 9a and colder, treat as a greenhouse or conservatory specimen. Provide full sun and keep nearly dry in winter.
Conservation
Aloidendron dichotomum is one of the best-studied examples of climate-driven range decline in the succulent flora. Modelling studies by Foden, Midgley et al. (2007) predicted significant range contraction under warming scenarios, and these predictions have been confirmed by subsequent field surveys. Throughout much of its range, the species is failing to recruit young trees — the population is ageing without replacement. The causes are complex: increasing temperatures reduce the survival of seedlings, shifting rainfall patterns disrupt the winter moisture on which the species depends, and extreme heat events kill established trees outright.
The Quiver Tree Forest near Keetmanshoop (Namibia) and the Gannabos forest in the Northern Cape (South Africa) are protected sites, but protection alone cannot address the underlying climatic shift. Aloidendron dichotomum has become a flagship species for climate-change communication in southern Africa, appearing on South African banknotes, postage stamps and tourism campaigns.
The cultural significance of the species extends deep into the indigenous history of the region. The San people used the hollowed-out branches as quivers for their arrows — a practice that gives the tree both its English and Afrikaans names. The San name “choje” is the oldest recorded name for the species.
Authority links
POWO (Plants of the World Online, Kew): https://powo.science.kew.org/taxon/…
PlantZAfrica (SANBI): https://pza.sanbi.org/aloidendron-dichotomum
IUCN Red List: https://www.iucnredlist.org/species/140661836/140666503
GBIF: https://www.gbif.org/species/9485745
Wikipedia: https://en.wikipedia.org/wiki/Aloidendron_dichotomum
iNaturalist: https://www.inaturalist.org/taxa/…
Dave’s Garden: https://davesgarden.com/guides/pf/go/56806
World of Succulents: https://worldofsucculents.com/…
Plant Lust: https://plantlust.com/plants/5556/aloe-dichotoma/
Bibliography
Grace, O.M., Klopper, R.R., Smith, G.F., Crouch, N.R., Figueiredo, E., Rønsted, N. & van Wyk, A.E. (2013). A revised generic classification for Aloe (Xanthorrhoeaceae subfam. Asphodeloideae). Phytotaxa 76: 7–14.
Manning, J.C., Boatwright, J.S., Daru, B.H., Maurin, O. & van der Bank, M. (2014). A molecular phylogeny and generic classification of Asphodelaceae subfamily Alooideae: a final resolution of the prickly issue of polyphyly in the alooids? Systematic Botany 39(1): 55–74. DOI: 10.1600/036364414X678044
Foden, W., Midgley, G.F., Hughes, G., Bond, W.J., Thuiller, W., Hoffman, M.T., Kaleme, P., Underhill, L.G., Rebelo, A.G. & Hannah, L. (2007). A changing climate is eroding the geographical range of the Namib Desert tree Aloe through population declines and dispersal lags. Diversity and Distributions 13: 645–653.
Masson, F. (1776). Aloe dichotoma. In: Philosophical Transactions of the Royal Society.
Reynolds, G.W. (1950). The Aloes of South Africa. Balkema, Cape Town.
Carter, S., Lavranos, J.J., Newton, L.E. & Walker, C.C. (2011). Aloes. The definitive guide. Kew Publishing, Royal Botanic Gardens, Kew.
Court, D. (2010). Succulent Flora of Southern Africa. Struik Nature, Cape Town.
Cousins, S.R. & Witkowski, E.T.F. (2012). African Aloe ecology: A review. Journal of Arid Environments 85: 1–17.