In the spiny forests of southern Madagascar — one of the most otherworldly landscapes on Earth — a solitary, unbranched alooid tree rises to four metres above the thorny thicket. Its long, rubbery leaves curve gently upward, tipped in soft, rounded ends rather than sharp points. Under the right conditions, it produces an extraordinarily long inflorescence of fragrant, tubular flowers that open at night — luring bats and perhaps mouse lemurs in the darkness of a Malagasy winter. It flowers only when it is at least twenty to thirty years old, and even then, not every year. It is one of the rarest, slowest-growing and most enigmatic alooids on the planet. Its name is Aloestrela suzannae.
Aloestrela is a monotypic genus — it contains a single species, Aloestrela suzannae, endemic to the extreme south of Madagascar. It is one of the most recently erected alooid genera (Smith & Molteno 2019) and one of the most taxonomically debated. Molecular studies have placed it as sister to Aloidendron eminens from Somalia, suggesting it may belong within Aloidendron rather than in a genus of its own. Yet POWO (Kew) and the latest CITES checklist (2025) accept Aloestrela as a valid genus. The question remains open — and the plant itself remains one of the most fascinating alooids in existence.
This page is the reference for the genus Aloestrela on our site. It covers the taxonomy, the controversy, the remarkable biology and the conservation of this Malagasy icon.
Taxonomy and classification
From Aloe to Aloestrela
The species was first described as Aloe suzannae by Raymond Decary in 1921, from material collected in southern Madagascar. Decary named it for his daughter Suzanne. For nearly a century, it remained classified within Aloe — an obviously arborescent species, but one with several features that set it apart from other tree aloes: its unbranched stem (no dichotomous forking), its soft, rubbery leaves with rounded tips and, most strikingly, its nocturnal, fragrant flowers.
When molecular phylogenetic studies in the 2010s showed that the traditional genus Aloe was not monophyletic, several segregate genera were erected — Aloidendron for the tree aloes, Aloiampelos for the rambling aloes, Aristaloe, Gonialoe, Kumara. But where did Aloe suzannae belong? It did not fit neatly into Aloidendron — it lacks the dichotomous branching that defines that genus. Some analyses suggested a closer relationship to Kumara (the fan aloe lineage) than to Aloe sensu stricto.
In 2019, Gideon Smith and Steven Molteno formally erected the monotypic genus Aloestrela (published in Bradleya 37: 3–7) for this species, arguing that its combination of morphological characters — unbranched arborescent habit, nocturnal fragrant flowers, soft rubbery leaves with rounded tips — warranted its recognition as a distinct evolutionary lineage. The genus name honours Professor Estrela Figueiredo of the Department of Botany at Nelson Mandela University in Gqeberha, South Africa.
The controversy: Aloestrela or Aloidendron?
In the same year that Aloestrela was erected, Malakasi et al. (2019) published a landmark museomics study using chloroplast genomes and nuclear ITS sequences from herbarium specimens, including the first molecular data ever obtained for Aloe suzannae. Their results placed A. suzannae as sister to Aloidendron eminens (from Somalia), firmly within the Aloidendron clade — with strong bootstrap support in both plastid (BP = 100) and nuclear (BP = 83) trees.
If this placement is correct, Aloestrela would not be a valid genus — the species would belong in Aloidendron, and the correct name would be Aloidendron suzannae. However, the morphological case for separating it remains strong: Aloestrela suzannae does not branch dichotomously (the defining character of Aloidendron), its flowers are nocturnal and fragrant (unique among alooids), and its leaves are distinctively soft and rounded — none of these characters match the Aloidendron diagnosis.
The taxonomic situation currently depends on the authority consulted:
POWO (Kew) accepts Aloestrela suzannae as a valid genus and species — Aloe suzannae is listed as a synonym.
CITES Checklist (2025) recognises Aloestrela as one of seven genera within the “aloe group” — alongside Aloe, Aloiampelos, Aloidendron, Aristaloe, Gonialoe and Kumara.
Molecular consensus (Malakasi et al. 2019) places the species within Aloidendron, which would make Aloestrela a synonym.
A comprehensive revision incorporating additional nuclear phylogenomic data (such as the approach used by Woudstra et al. 2025 for other alooids) will be needed to resolve this question definitively. Until then, we follow POWO in using Aloestrela.
Position in the alooid group
Aloestrela belongs to the family Asphodelaceae, subfamily Asphodeloideae, within the alooid clade. Molecular data from Malakasi et al. (2019) place it within the “true aloe” clade — specifically as sister to Aloidendron eminens in the eastern sub-clade of tree aloes. Morphological data (Smith & Molteno 2019, PlantZAfrica/SANBI) have also suggested a closer relationship to Kumara than to Aloe sensu stricto, though this has not been confirmed by all molecular analyses.
Distribution and habitat
Aloestrela suzannae is endemic to the extreme south of Madagascar, occurring in the districts of Ampanihy and Taolagnaro (Fort-Dauphin). It was formerly also known from Ambovombe-Androy and Amboasary-Sud, but it is now thought to be locally extinct in these areas — a grim indicator of the conservation pressures facing this species.
The habitat is the spiny forest (fourré épineux) of southern Madagascar — one of the most distinctive biomes on Earth. This is a dry, thorny thicket dominated by Didiereaceae (the “octopus trees”), succulent Euphorbia and other drought-adapted endemics. Aloestrela suzannae grows in sandy soil and on limestone substrate, in the shade of the surrounding thorny vegetation — like many alooids, it is a shade-dependent plant that relies on nurse plants for establishment. Annual rainfall is very low — typically less than 500 mm — and the climate is hot and dry for most of the year.
Morphology: the unbranched tree aloe
Growth form: solitary, single-stemmed, arborescent. Unlike Aloidendron — which branches dichotomously — Aloestrela suzannae never branches. The plant grows as a single, tall column topped by a rosette of leaves, more reminiscent of a Dracaena or a columnar cactus than a typical aloe. This is the most visually distinctive character separating it from the tree aloes proper. Mature plants reach approximately four metres tall with a trunk diameter of about twenty-five centimetres.
Leaves: arranged in a dense rosette at the apex of the stem. Lanceolate, curved upward, typically about fifty to sixty centimetres long. The texture is soft and rubbery — remarkably different from the firm, hard leaves of Aloidendron species. The surface is rough to the touch, lacking spots but bearing scattered small prickles. The margins have small triangular teeth. The leaf tips are blunt and rounded — not sharp-pointed as in almost all other alooids. Leaf colour is a rich green with subtle bluish, pinkish and grey tones that can shift with the seasons and light conditions.
Flowers: the most remarkable feature of this species. Flowering occurs only on mature plants at least twenty to thirty years old, and even mature plants do not flower every year. The inflorescence is exceptionally long — a tall, branched panicle that rises well above the leaf rosette — and lasts for over a month. The individual flowers are tubular, pale and fragrant, opening at night. This nocturnal flowering habit is unique among alooids — no other genus in the alooid clade is known to have nocturnal flowers. The pollinators are presumed to be bats and possibly nocturnal lemurs (such as mouse lemurs), though this has not been definitively confirmed. The flowers have also been observed open during the day in the wild.
Fruit and seed: capsules that dry and split open to release winged seeds.
Roots: fleshy, succulent — adapted to sandy, porous soils.
Growth rate: extremely slow. This is one of the slowest-growing alooids — plants take decades to reach their full stature and reproductive maturity. A specimen in a botanical garden may take twenty years or more to flower for the first time.
Cultivation
Aloestrela suzannae is a challenging plant to grow — not because it is fussy about conditions, but because it is excruciatingly slow and extremely frost-sensitive. It is a plant for patient collectors in warm climates or heated greenhouses.
Light: bright indirect light to partial shade. In habitat, plants grow in the dappled shade of the spiny forest understorey — they do not appreciate hot, direct afternoon sun. Morning sun or bright filtered light is ideal.
Substrate: well-drained, sandy, slightly acidic. The species grows naturally on sandy soil and limestone substrate. A mineral-rich mix with excellent drainage — 60 % coarse sand or pumice, 40 % quality compost — mimics the natural substrate. The plant does not tolerate waterlogging.
Watering: moderate in the growing season (spring through autumn), reduced in winter. Despite its arid habitat, Aloestrela suzannae appreciates regular moisture when actively growing — it grows faster (by its very slow standards) with consistent watering during warm weather. Always allow the substrate to dry between waterings.
Temperature: tropical — this is a frost-intolerant species. It requires a minimum temperature of approximately 5 °C, and ideally above 10 °C in winter. Any frost will cause severe damage or death. In frost-prone climates (including the Mediterranean coast and most of mainland Europe), it must be grown under glass or indoors year-round. In California, coastal Southern California and similar frost-free climates, it can be grown outdoors.
Growth rate: extremely slow. Even in ideal conditions, expect only a few centimetres of growth per year. Flowering may take twenty to thirty years from seed. This is a plant for collectors who measure progress in decades.
Container growing
Aloestrela suzannae adapts well to container culture — indeed, in most climates, this is the only practical option. A large, deep pot with excellent drainage is essential. The plant will remain compact and manageable for many years due to its slow growth rate. It makes an unusual and striking conservatory specimen — the soft, rubbery, blue-green leaves and the columnar, unbranched form are unlike anything else in a succulent collection.
Propagation
From seed: the primary method. Germination occurs at 20–25 °C, typically within two to four weeks. Seedlings are tiny and grow very slowly — do not expect rapid results. Fresh seed gives the best germination rates.
From offsets or cuttings: not applicable — Aloestrela suzannae is a solitary, unbranched species that does not produce offsets and cannot be propagated vegetatively.
The combination of no vegetative propagation, extremely slow growth and infrequent flowering makes this a difficult species to produce commercially. Most plants in cultivation originate from seed collected from botanical garden specimens or (historically) from wild populations — a practice that has contributed to the species’ decline in habitat.
Conservation: a species in crisis
Aloestrela suzannae is listed as Endangered on the IUCN Red List and is considered one of the most threatened alooids in the world. The threats are severe and compounding:
Habitat destruction: the spiny forest of southern Madagascar is being cleared at an alarming rate for slash-and-burn agriculture (tavy), charcoal production and cattle grazing. This biome — which exists nowhere else on Earth — has lost over 50 % of its original extent, and the rate of loss is accelerating.
Local extinction: Aloestrela suzannae is already thought to be locally extinct in parts of its former range (Ambovombe-Androy, Amboasary-Sud). The remaining populations are fragmented and isolated.
Over-collection: the species’ rarity and unusual appearance make it highly desirable for the succulent plant trade. Wild collection — both legal and illegal — has depleted already small populations.
Slow reproduction: the species’ extreme slowness, solitary habit (no vegetative reproduction) and infrequent flowering mean that populations recover very slowly from any disturbance. A plant removed from the wild may represent twenty to thirty years of growth that cannot be replaced.
The species is listed under CITES Appendix II, meaning international trade is regulated. However, enforcement in Madagascar is limited. Conservation efforts focus on protecting the remaining spiny forest habitat — but the pressures of poverty, population growth and climate change in southern Madagascar make this an enormous challenge. Every Aloestrela suzannae in cultivation should be from propagated stock — never wild-collected.
Web resources
Plants of the World Online (POWO) — Kew Royal Botanic Gardens. Accepts Aloestrela suzannae as a valid genus and species. powo.science.kew.org
PlantZAfrica — South African National Biodiversity Institute (SANBI). A detailed species page for Aloestrela suzannae including morphology, distribution, ecology and conservation status. pza.sanbi.org
IUCN Red List (iucnredlist.org). Conservation assessment for the species (listed under Aloe suzannae). Distribution maps and population data.
iNaturalist (inaturalist.org). Citizen-science observations from Madagascar and botanical gardens. Search “Aloestrela suzannae” or “Aloe suzannae.”
Kirstenbosch National Botanical Garden / SANBI. Maintains living specimens of Aloestrela suzannae — one of the few institutions where the plant can be seen outside Madagascar.
Bibliography
The genus description
Smith G.F., Molteno S. (2019). Aloestrela Molteno & Gideon F. Sm. (Asphodelaceae: Alooideae), a new alooid genus with A. suzannae (Decary) Molteno & Gideon F. Sm. as the only species. Bradleya, 37: 3–7. — The paper that established the genus.
Taxonomy and phylogenetics
Decary R. (1921). Aloe suzannae sp. nov. Bulletin Économique de Madagascar, 18(1): 26. — The original species description.
Malakasi P., Bellot S., Leitch I.J., Grace O.M. (2019). Museomics clarifies the classification of Aloidendron (Asphodelaceae), the iconic African tree aloes. Frontiers in Plant Science, 10: 1227. — The key molecular study. Found A. suzannae sister to Aloidendron eminens within the Aloidendron clade (BP = 83–100). If confirmed by further analyses, this would make Aloestrela a synonym of Aloidendron.
Grace O.M., Klopper R.R., Figueiredo E., Smith G.F. (2013). A revised generic classification for Aloe (Xanthorrhoeaceae subfam. Asphodeloideae). Phytotaxa, 76: 7–14. — The paper that initiated the splitting of Aloe into multiple genera. A. suzannae was not placed in a separate genus at this stage.
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. Systematic Botany, 39(1): 55–74.
Dee R., Malakasi P., Rakotoarisoa S.E., Grace O.M. (2018). A phylogenetic analysis of the genus Aloe (Asphodelaceae) in Madagascar and the Mascarene Islands. Botanical Journal of the Linnean Society, 187: 428–440. — Important for understanding the broader context of Malagasy aloes.
Woudstra Y., Grace O.M., Klopper R.R. et al. (2025). Nuclear phylogenomics reveals strong geographic patterns in the evolutionary history of Aloe and related genera (alooids). Annals of Botany. — Confirms the monophyly of the major alooid genera using nuclear data.
General references
Carter S., Lavranos J.J., Newton L.E., Walker C.C. (2011). Aloes: The Definitive Guide. Kew Publishing. — Covers A. suzannae under Aloe.
Castillon J.-B., Castillon J.-P. (2010). Les Aloe de Madagascar. — The most comprehensive treatment of Malagasy aloes.
Rakotoarisoa S.E., Klopper R.R., Smith G.F. (2014). Conservation status assessment of Malagasy aloes. — Found that approximately 39 % of Malagasy aloes are threatened.
Going further
The genus Aloestrela contains just one species — but what a species. Aloestrela suzannae is a plant of superlatives and paradoxes: the only alooid with nocturnal, fragrant flowers; the only unbranched tree aloe; one of the slowest-growing succulents in cultivation; endangered in its only habitat, the vanishing spiny forests of Madagascar; and at the centre of an unresolved taxonomic debate that asks whether it is truly a genus of its own or a deeply divergent member of Aloidendron. For the patient collector who can provide warmth, patience and a very long timeline, Aloestrela suzannae is one of the most rewarding alooids to grow — a living connection to one of the most extraordinary ecosystems on Earth. Our site offers care guides, taxonomic references and conservation information for every alooid genus.