The aloe tribe is one of the richest groups of succulents for gardeners and collectors alike. It spans an extraordinary range — from tree-sized Aloidendron barberae towering at 18 m (60 ft) to thumbnail-sized Haworthia that fit inside an espresso cup. What unites them is a shared ancestry within the subfamily Asphodeloideae, a preference for well-drained soil, and fleshy, often translucent leaves arranged in rosettes of sometimes breathtaking geometry.
Unlike the agavoids — their New World counterparts with rigid, fibrous leaves — alooids have soft, gel-filled tissues and a distinctly different feel. Break an agave leaf and you’ll find tough fibres; break an aloe leaf and you’ll find clear, viscous gel. This fundamental difference reflects separate evolutionary paths on different continents: agavoids evolved in the Americas, aloeoids in Africa.
The taxonomy of this group has been revolutionised since 2013. If you learned your aloe names before then, many have changed. The old genus Aloe has been split into six genera; the old genus Haworthia into three. This guide explains the new classification, introduces each genus, and provides practical growing advice for gardeners in the US, UK, and other temperate climates.
Why the names changed: the 2013 revolution
For over a century, the genus Aloe was a catch-all for any African succulent rosette with tubular flowers. Similarly, Haworthia lumped together soft-leaved and hard-leaved species that looked very different from one another.
Molecular phylogenetic studies — principally Grace et al. (2013) for Aloe and Manning et al. (2014) for Haworthia — demonstrated that both genera were not monophyletic: some species traditionally placed in Aloe were more closely related to Haworthia or Gasteria than to the core group of aloes. The solution was to split both genera into smaller, genetically coherent units.
The practical consequence: the plant that nurseries still sell as “Aloe variegata” is now properly Gonialoe variegata; “Aloe aristata” is Aristaloe aristata; “Aloe plicatilis” is Kumara plicatilis; “Haworthia attenuata” is Haworthiopsis attenuata. The old names remain in widespread commercial use, and most growers will recognise both — but the new names reflect genuine evolutionary relationships, and this guide uses them throughout.
Growing aloeoids: key differences from agavoids
If you’re accustomed to growing agaves and yuccas, aloeoids require a few adjustments.
Light: many prefer shade
This is the biggest surprise for growers coming from the agavoid world. While large garden aloes (Aloe arborescens, Aloe maculata, the Aloidendron species) need full sun, the smaller genera — Haworthia, Haworthiopsis, Gasteria, Tulista, Gonialoe — thrive in bright indirect light or morning sun only. In the wild, many of these plants grow wedged in rock crevices or under shrubs, shielded from the brutal afternoon sun of the South African veld. Hot direct sun can bleach their colours and scorch their leaves.
For indoor growers in the US and UK, this is excellent news: Haworthia, Haworthiopsis, and Gasteria are among the very few succulents that genuinely do well on an east-facing windowsill or under moderate artificial light.
Substrate
Drainage remains essential, but aloeoids tolerate — and often prefer — a slightly richer mix than agavoids. A 50/50 blend of mineral matter (pumice, perlite, coarse sand) and lightweight organic compost works well. Pure mineral substrates, while safe, often result in slower growth and less turgid leaves compared to a slightly organic mix.
Watering
Aloeoids need more frequent watering during active growth than agavoids. Many species — especially those from the winter-rainfall regions of the Western Cape — grow primarily in autumn, winter, and spring, resting in summer heat. In pots, water when the top inch of substrate is dry during the growing season (typically every 7–10 days); reduce significantly in summer for winter-growers, and in winter for summer-growers. Never leave water sitting in saucers.
Cold hardiness
The range is enormous: Aloiampelos striatula tolerates −10/−12 °C (10/14 °F); most Haworthia and Gasteria are damaged below −2 °C (28 °F). Wet cold is always more dangerous than dry cold. In the US, outdoor year-round culture of the hardier species is possible in USDA zones 9–11 (and zone 8 for a handful of tough species). In the UK/large part of Europe, all but the hardiest aloes and relatives are pot plants with winter protection.
The core genera of the aloe tribe
Genus Aloe
The central genus: approximately 600 species distributed from southern Africa to the Arabian Peninsula, through Madagascar and the Indian Ocean islands. Rosettes range from a few centimetres (Aloe descoingsii) to several metres across. Flowers are tubular, typically red, orange, or yellow, borne on tall racemes that are pollinated by sunbirds in the wild. Aloe is the only genus of the tribe with significant distribution outside southern Africa.
Garden-worthy species for temperate climates include Aloe maculata (spotted aloe, hardy to −4 °C / 25 °F), Aloe arborescens (torch aloe, hardy to −5 °C / 23 °F), and Aloe vera (the most commercially important species, but one of the least frost-tolerant). For more on telling aloes from their look-alikes, see our guide to agave vs aloe.
Genus Gasteria
About 23 species, all South African. Recognised by their thick, tongue-shaped leaves arranged in two ranks (distichous) in young plants, becoming spiralled with age. The name refers to the stomach-shaped flowers. Gasteria are among the most shade-tolerant succulents in existence — they thrive in low-light conditions where most other succulents fail. Extremely easy to grow, they multiply readily by offsets and make outstanding houseplants for poorly lit rooms.
Genus Haworthia (sensu stricto)
After the 2013–2014 revision, Haworthia in the strict sense refers to the “soft” haworthias: small rosettes with tender, often translucent leaves bearing “windows” — transparent areas that channel light to internal photosynthetic tissue. This adaptation allows the plants to grow partially buried in soil or in deep rock crevices, exposing only their leaf tips to the sun. About 150 accepted species, nearly all endemic to South Africa. Haworthia are enormously popular in East Asian collecting circles, where rare forms command extraordinary prices.
Genus Haworthiopsis
Created by Rowley in 2013 for the former “hard” haworthias (subgenus Hexangulares). Leaves are tough and leathery, typically covered in raised white tubercles forming horizontal bands — hence their common name “zebra plants”. About 18 species. The two most common in commerce are Haworthiopsis attenuata and Haworthiopsis fasciata, which are among the most widely sold succulents in the world — every garden centre stocks them, usually under the old name Haworthia.
Go to genus Haworthiopsis page.
Genus Tulista
A small genus (~4 species) segregated from Haworthia subgenus Robustipedunculatae. Larger and more robust than typical haworthias, with thick triangular leaves bearing prominent white protuberances. Tulista pumila (formerly Haworthia pumila) is the best-known species.
Genus Astroloba
About 10 South African species forming tight columns or towers of small, hard, spirally arranged leaves — almost architectural in their geometric precision. Slow-growing, easy in cultivation, with care similar to Haworthiopsis. Phylogenetically closer to Tulista and Haworthiopsis than to Aloe.
Genera split from Aloe since 2013
Five genera were separated from Aloe in 2013 (Grace et al.), recognising that the traditional genus was not monophyletic; a sixth, Aloestrela, followed in 2019 (Smith & Molteno). The old names remain in widespread commercial use; the new names and their correspondences are given below.
Genus absorbed into Aloe: Lomatophyllum
The 2013 reclassification did not only split genera from Aloe — it also merged one into it. Lomatophyllum (Willdenow 1811) was a genus of about fifteen species from Madagascar and the Mascarene Islands (Mauritius, Réunion) that looked identical to Aloe in every respect except one: their fruits are fleshy, indehiscent berries rather than the dry, splitting capsules of typical aloes. This single character — fruit type — was the traditional justification for keeping them separate.
Molecular studies (Grace et al. 2013, Manning et al. 2014) showed that the berry-fruited species are nested within Aloe sensu stricto and do not form a distinct lineage: the fleshy fruit evolved independently several times within Aloe and does not warrant a separate genus. All Lomatophyllum species have been transferred to Aloe, and Lomatophyllum is now a synonym.
The best-known former members include Aloe tormentorii (Mauritius), Aloe purpurea (Mauritius) and Aloe macra (Réunion). The 2013 revision thus worked in both directions: genera that were too different to remain within Aloe were separated out, while a genus that was too similar to remain separate was absorbed back in.
Genus Aloidendron — the tree aloes
The giants of the group: single-trunked or branching trees reaching 10–18 m (33–60 ft). Aloidendron barberae (formerly Aloe barberae / Aloe bainesii) is the largest “aloe” in the world — a genuine tree, not a rosette. Aloidendron dichotomum (the quiver tree) is an icon of the Namibian landscape. These are plants for frost-free or near-frost-free climates only (USDA 10–11), though Aloidendron dichotomum tolerates brief frosts to −5 °C (23 °F) when dry.
Genus Aloiampelos — the scrambling aloes
Aloes with elongated, climbing or sprawling stems that lean on surrounding vegetation. The most important species for temperate gardeners is Aloiampelos striatula (formerly Aloe striatula): one of the hardiest aloeoids, tolerating −10 to −12 °C (10 to 14 °F) in well-drained soil. It forms dense, sprawling hedges with yellow summer flowers and is increasingly planted in coastal UK gardens and the Pacific Northwest. An outstanding plant for covering banks and walls.
Go to the genus Aloiampelos page.
Genus Aloestrela — the nocturnal tree aloe of Madagascar
A monotypic genus containing a single species, Aloestrela suzannae (formerly Aloe suzannae), endemic to the vanishing spiny forests of southern Madagascar. An unbranched, solitary succulent tree reaching about 4 m (13 ft) — it never forks dichotomously like Aloidendron, growing instead as a single column topped by a rosette of soft, rubbery, blue-green leaves with distinctively rounded tips. Its most remarkable feature is unique among all alooids: nocturnal, fragrant flowers, presumably pollinated by bats and possibly mouse lemurs — no other genus in the group produces night-blooming flowers. Plants take 20–30 years to reach flowering maturity and cannot be propagated vegetatively (no offsets, no cuttings — seed only).
The genus was erected by Smith & Molteno in 2019 and is accepted by POWO and the CITES checklist, but molecular data (Malakasi et al. 2019) place Aloestrela suzannae as sister to Aloidendron eminens within the Aloidendron clade — its generic status remains debated. Strictly frost-intolerant (minimum 5 °C / 41 °F) and Endangered on the IUCN Red List.
Go to the genus Aloestrela page.
Genus Aristaloe — the lace aloe
A monotypic genus: one species only, Aristaloe aristata (formerly Aloe aristata). A small, stemless rosette (10–15 cm / 4–6 in) with dark green leaves covered in white tubercles and tipped with long, soft bristles (aristae). Frequently confused with a haworthia — and for good reason: molecular data shows it is more closely related to Haworthia than to the core Aloe group. Very hardy (−7 to −10 °C / 19 to 14 °F in dry soil), clumping, easy. An excellent beginner plant and one of the best aloeoids for outdoor culture in USDA zone 8.
Go to the genus Aristaloe page.
Genus Gonialoe — the tiger aloe
Three species, of which Gonialoe variegata (formerly Aloe variegata) is the most famous: a compact rosette with triangular leaves bearing striking white transverse bands. Probably the most widely grown aloeoid houseplant in the world. Shade-tolerant, easy, flowers readily indoors. Hardy to about −3 °C (27 °F).
Go to the genus Gonialoe page.
Genus Kumara — the fan aloe
Two species: Kumara plicatilis (formerly Aloe plicatilis), the fan aloe, with distichous leaves arranged like the pages of an open book on branching stems — one of the most architecturally striking succulents in existence. Native to the Western Cape fynbos. Winter-growing, intolerant of hot, humid summers. Hardy to −4/−5 °C (23/25 °F). A magnificent pot plant for cool-summer climates (coastal UK, Pacific Northwest, San Francisco Bay Area). And the rarer Kumara haemanthifolia, with broad, flat leaves.
Allied genera
These plants belong to the same subfamily (Asphodeloideae) but not to the aloe tribe. They share similar origins and growing conditions and are often planted alongside aloeoids.
Genus Bulbine
Small herbaceous or shrubby succulents with cylindrical or flattened leaves and delicate yellow or orange flowers on slender stems. Bulbine frutescens is widely used as a ground cover in Mediterranean and Californian gardens — fast-growing, drought-tolerant, and nearly indestructible in frost-free areas. Hardy to about −4 °C (25 °F).
Genus Kniphofia (red hot pokers)
Herbaceous perennials with strap-like leaves and spectacular spikes of tubular flowers in fiery reds, oranges, and yellows. Not succulents, but they share the Asphodelaceae family and associate beautifully with large aloes in dry-garden compositions. Many species are hardy to −15 °C (5 °F) or below, making them growable across virtually all of the US and UK. Kniphofia uvaria and its hybrids are widely available in US and UK nurseries.
Genera Asphodelus & Asphodeline
The asphodels — familiar wild plants of the Mediterranean, with narrow leaves and tall racemes of white or yellow flowers. Asphodelus species are weedy in parts of California and Australia. They share the Asphodelaceae family with aloeoids and the same deep drought tolerance.
Genus Phormium
New Zealand flax (Phormium tenax and Phormium cookianum) — strap-leaved plants that bring a very different texture to agavoid plantings. Available in a stunning range of cultivar colours: bronze, red, pink-striped, olive. Hardy to about −8/−10 °C (14/18 °F). Widely grown in the UK, Pacific Northwest, and coastal California.
Genus Xanthorrhoea
The Australian grass trees — ancient, slow-growing plants with blackened trunks topped by grass-like tufts of leaves. Spectacular in the right setting but very slow to establish (expect years, not months, of visible growth). Hardy to about −5 °C/−8 °C (18/23 °F); requires perfect drainage and acid to neutral soil.
Hybridisation: a defining feature of the group
One of the most remarkable characteristics of the aloe tribe is the ease with which its genera hybridise — both in the wild and in cultivation. Intergeneric crosses include:
- × Gasteraloe (Gasteria × Aloe) — the most common, combining the shade tolerance of Gasteria with the vigour of Aloe.
- × Gasterhaworthia (Gasteria × Haworthia)
- × Alworthia (Aloe × Haworthia)
- × Gonialoe hybrids and various complex crosses involving Astroloba
This genetic permeability has produced hundreds of hybrids and cultivars, many of outstanding ornamental quality. It also explains much of the nomenclatural confusion surrounding this group: plants with mixed ancestry don’t always fit neatly into genus-level categories. For collectors, hybridisation is both an opportunity (infinite variety) and a hazard (mislabelled plants are everywhere).
Choosing aloes and relatives for your climate
| USDA Zone | Approx. min. temp. | Suitable genera and species |
|---|---|---|
| 7b–8 | −12 to −10 °C (10 to 14 °F) | Aloiampelos striatula, Aristaloe aristata |
| 9 | −4 to −7 °C (19 to 25 °F) | Above + Aloe arborescens, Aloe maculata, Aloe ferox, Kumara plicatilis, Aloidendron dichotomum, Bulbine frutescens |
| 10–11 | Above −1 °C (30 °F) | All genera, including Aloe vera, Aloidendron barberae, Gonialoe variegata, tropical Aloe species |
| Indoors (any zone) | Above 5 °C (41 °F) | Haworthia, Haworthiopsis, Gasteria, Tulista, Gonialoe variegata, Astroloba — all excellent windowsill plants |
Further reading on succulentes.net
- The genus Aloe: all species profiles
- Kumara plicatilis (fan aloe): species profile
- Aristaloe aristata (lace aloe): species profile
- Aloe polyphylla (spiral aloe): species profile
- Aloidendron barberae (tree aloe): species profile
- Agave vs Aloe: how to tell them apart
- Agavoids: the companion guide to Agave, Yucca and related genera
- Aloe thrips (Hercinothrips dimidiatus): identification and control
Selected references
Gildenhuys, S.D. & Klopper, R.R. (2016). A synoptic review and new infrageneric classification for Haworthiopsis. Phytotaxa, 265(1): 1–26.
Grace, O.M., Klopper, R.R., Smith, G.F. et al. (2013). A revised generic classification for Aloe (Xanthorrhoeaceae subfam. Asphodeloideae). Phytotaxa, 76(1): 7–14.
Manning, J., Boatwright, J.S., Daru, B.H. et al. (2014). A molecular phylogeny and generic classification of Asphodelaceae subfamily Alooideae. Systematic Botany, 39(1): 55–74.
Reynolds, G.W. (1950). The Aloes of South Africa. A.A. Balkema, Cape Town.
Bayer, M.B. (1999). Haworthia Revisited. Umdaus Press, Pretoria.
Carter, S., Lavranos, J.J., Newton, L.E. & Walker, C.C. (2011). Aloes: The Definitive Guide. Kew Publishing.
Van Wyk, B.-E. & Smith, G.F. (2014). Guide to the Aloes of South Africa. Briza Publications.
Rowley, G.D. (2013). Haworthiopsis: a new genus. Alsterworthia International, Special Issue 10.