Cycas thouarsii

Cycas thouarsii is the only cycad of its genus native to Africa and Madagascar: a large cycad of the coastal forests of eastern Madagascar, the Comoros and the coasts of Kenya and Tanzania, with big red seeds that float. Named after the French botanist Aubert du Petit-Thouars, it belongs to the group of coastal, floating-seeded species of the genus Cycas. According to a specialist nursery, it is also the plant sold in garden centres under the wrong name “Cycas circinalis”. It tolerates only brief, light frosts.

Key facts about Cycas thouarsii

  • Accepted name: Cycas thouarsii R.Br. (1810), accepted by The World List of Cycads (version 2026.08.15); the World Checklist of Vascular Plants (WCVP), on which POWO is based, also accepts it (consulted through GBIF on 31 October 2026)
  • Synonyms: Cycas madagascariensis Miq. (1840), Cycas comorensis Bruant (1888), Cycas circinalis subsp. thouarsii (R.Br.) Engl. (1908), Cycas circinalis f. trigonocarpoides J.Schust. (1932)
  • Family: Cycadaceae, order Cycadales; subsection Rumphiae according to Hill, subgenus Cycas according to de Laubenfels and Adema (see Taxonomy)
  • Common names: Madagascar cycad (Species+); “faux sagoutier” in French, fahou in Malagasy, mpapindi in Swahili
  • Natural range: eastern Madagascar, the Comoros, the coast of Kenya and Tanzania, including Zanzibar
  • IUCN status: Least Concern (LC); assessment by J. D. Bösenberg published in 2024
  • CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: foliage scorched from 0 to −1 °C (32 to 30.2 °F), almost entirely at −2 to −3 °C (28.4 to 26.6 °F); one plant probably lost after −5 °C (23 °F) in Sicily (growers’ reports, see Cold hardiness)
  • Light and soil: in the wild, seashore vegetation and humid lowland forest; in cultivation, sun or part shade, warmth, free-draining soil
  • Habit and adult size: trunk up to 10 m tall and 45 cm across, often branched; leaves 1.5 to 3 m long
  • In the UK, US and Australia: declared by Kew and Glasgow (BGCI); in the US at Montgomery Botanical Center (nine accessions), Fairchild and some twenty other gardens; in Australia at the Royal Botanic Garden Sydney (seven plants) and in outdoor beds at the Royal Botanic Gardens Victoria, Melbourne
  • Toxicity: no analysis specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas thouarsii

Cycas thouarsii is recognised by its large flat leaves, by its male cones in which each scale ends in a short, clearly hooked point, and above all by its big red seeds, 54 to 60 mm long, which float (de Laubenfels and Adema 1998).

According to the revision by de Laubenfels and Adema (1998), the only complete modern description consulted, the trunk reaches 10 m in height and 45 cm in diameter; it tapers upwards and often branches. The leaves are 150 to 300 cm long and carry 60 to 120 leaflets on each side. The petiole, 30 to 50 cm long, is spiny along most of its length. The leaflets are lance-shaped, 17 to 31 (35) cm by 8 to 13 (15) mm, with the midrib more prominent beneath.

The male cones are cylindrical, 30 to 60 cm by 10 to 15 cm. Each microsporophyll, 15 to 17 mm wide, ends in a sterile part of 12 to 15 mm, extended into a point of 5 to 8 mm that is strongly hooked. The megasporophylls carry 4 to 10 ovules and a lance-shaped, long-pointed blade, 60 to 80 mm by 20 to 25 mm, with small teeth of 2 to 3 mm at most and a tip of 10 to 30 mm. The red seeds measure 54 to 60 mm by 42 to 50 mm and float thanks to a spongy layer. They take two years to ripen (Lindstrom, Hill and Stanberg 2009).

Hybrids

No natural hybrid is known: the species grows far from every other Cycas. In cultivation, Cycas thouarsii has been crossed with blue-leaved Australian species, Cycas cairnsiana, Cycas couttsiana and Cycas cupida, to obtain a fast-growing blue cycad, according to a specialist nursery writing on the French forum Fous de palmiers in 2013. On the Côte Bleue, west of Marseille, a gardener described the growth of the hybrid Cycas thouarsii × Cycas cairnsiana as “impressive” in 2013 and then planted it in the ground. No source documents a better cold tolerance for these hybrids.

Possible confusion

The “Cycas circinalis” of garden centres

The confusion is old. Du Petit-Thouars himself illustrated the plant of Madagascar in 1804 under the name Cycas circinalis, and Engler (1908) and then Schuster (1932) made it a subspecies of that species (de Laubenfels and Adema 1998). It carries on in the trade. A specialist nursery stated in 2019 and 2020, on the French forum Fous de palmiers, that the plants sold in garden centres as Cycas circinalis are Cycas thouarsii, and that every “circinalis” and “rumphii” he had seen for sale in Europe was Cycas thouarsii. The same observation appears in Italy as early as 2009 on the forum Tropicamente. Growing reports published under the name Cycas circinalis therefore probably often concern this species, and botanic gardens are not immune: in 2010 a study at the Royal Botanic Garden Edinburgh found that three of its four plants labelled Cycas circinalis were in fact Cycas rumphii (Clugston 2010). The same study notes that Cycas circinalis has a broad, wavy megasporophyll blade, less marked in Cycas thouarsii.

How to tell it from related species

  • Cycas circinalis, from India: smaller seeds (30 to 39 mm), without a spongy layer and not floating; microsporophylls ending in a long straight point of 20 to 39 mm (Lindstrom and Hill 2007; de Laubenfels and Adema 1998).
  • Cycas rumphii, from eastern Indonesia: microsporophylls almost without a point (2 to 5 mm), seeds with a crest on top of the shell, broader leaflets (12 to 18 mm).
  • Cycas seemannii, from Fiji and neighbouring islands: petiole with few or no spines, microsporophylls with a short point of 4 to 5 mm (de Laubenfels and Adema 1998, under Cycas celebica).
  • Cycas zeylanica, from Sri Lanka and the Andaman and Nicobar Islands: close, with the same uncrested seed and a pointed microsporophyll, but with long, prickly cataphylls and widely spaced leaflets (Lindstrom and Hill 2007).

Taxonomy

The World List of Cycads attributes the name to Robert Brown, who published it in 1810 in his Prodromus Florae Novae Hollandiae, spelt “thuarsii” and followed by a question mark. De Laubenfels and Adema (1998) regarded Brown’s name as a bare name and attributed valid publication to Gaudichaud (1826); Lindstrom and Hill (2007) write “Gaudich. ex R.Br.”. The type is a collection made by Du Petit-Thouars in Madagascar and kept at the Paris herbarium (P).

The place of the species within the genus differs between authors. Hill (1994) grouped the cycads whose seeds have a spongy layer in subsection Rumphiae; Lindstrom, Hill and Stanberg (2009) place Cycas thouarsii there, and confirm in it the two-year seed ripening that is another feature of the group. De Laubenfels and Adema (1998), on the other hand, placed it in subgenus Cycas, with Cycas circinalis, because of its elongated microsporophylls, while suggesting that their subgenus Truncata, that of Cycas rumphii, might derive from plants close to Cycas thouarsii.

The two revisions also differ on the range. De Laubenfels and Adema (1998) included in Cycas thouarsii the plants of Sri Lanka, described as Cycas rumphii subsp. zeylanica. Lindstrom and Hill (2007) treat them as a separate species, Cycas zeylanica. The World List of Cycads, which this site follows, adopts this treatment and restricts Cycas thouarsii to East Africa, Madagascar and the Comoros.

Etymology and history

The epithet honours Louis-Marie Aubert du Petit-Thouars (1758–1831), a French botanist who studied the flora of Madagascar and the Mascarenes (Haynes 2022). He illustrated the plant as early as 1804 in his Histoire des végétaux recueillis dans les îles australes d’Afrique, under the name Cycas circinalis (de Laubenfels and Adema 1998). Stapf (1916) devoted a study to it in the Kew Bulletin, and Vorster and Vorster (1986) an article in the journal Encephalartos.

De Laubenfels and Adema (1998) stress the puzzle of its range, very far from that of every other Cycas. They put forward two explanations: seeds carried by the sea, or transport by people, since the plant is still grown locally in Madagascar as a food plant. Neither explanation has been demonstrated.

Common names

Species+ gives Madagascar cycad in English, “faux sagoutier” in French, fahou in Malagasy and mpapindi in Swahili. The Royal Botanic Garden Sydney labels its plants “Batsimisaraka”. In the trade the plant is often sold as “Cycas circinalis”.

In the wild

The World List of Cycads restricts Cycas thouarsii to Madagascar, the Comoros, Kenya and Tanzania, including Zanzibar. De Laubenfels and Adema (1998) also recorded it in the Zambezi delta in Mozambique, and Species+ adds the Seychelles; these records are not accepted by The World List of Cycads. In Madagascar, the species grows along the east coast (de Laubenfels and Adema 1998).

It grows in seashore vegetation in regions of humid forest and in humid lowland forest, up to at least 500 m (de Laubenfels and Adema 1998). Its seeds float, which allows dispersal by sea.

Conservation status and regulation

The IUCN lists Cycas thouarsii as Least Concern (LC), in the assessment by J. D. Bösenberg published in 2024; the category is confirmed by the IUCN list relayed by GBIF and by The World List of Cycads (consulted on 21 October 2026). The previous assessment, by J. Golding and J. Hurter, dates from 2010.

Like the whole family Cycadaceae, the species has been listed in CITES Appendix II since 4 February 1977, with annotation #4 (CoP20 version, in force since 5 March 2026), which exempts seeds, pollen and seedlings or tissue cultures obtained in vitro in sterile containers; live plants still need permits. The United Kingdom, the United States and Australia apply CITES through their own national legislation; in the European Union the species is in Annex B of Regulation (EC) No 338/97, whose annexes in force are set by Commission Regulation (EU) 2026/1383, applicable since 29 June 2026. This general information does not replace the official texts: check the rules in force before buying or exchanging plants, and prefer plants raised from seed in cultivation.

Growing Cycas thouarsii

In short: a warm-climate cycad, reputed on growers’ forums to grow fast for a cycad, that can live outdoors only where frost is rare and brief; elsewhere it is a container plant for a bright, frost-free glasshouse or conservatory.

Outdoor and in-ground cultivation

In its native range it grows in a frost-free tropical coastal climate. In cultivation, the most useful outdoor experience comes from the Mediterranean, relevant to readers in comparable climates such as coastal California or southern Australia. On the Côte Bleue, west of Marseille, in the south of France, a gardener grows it in the ground facing the sea; in 2018 he judged it “not the toughest” of his cycads but viable in a sheltered spot, happy in full sun, with growth limited by a warm season that is too short. A young plant planted there came through the winter of 2013–2014 unharmed, a winter without any sub-zero temperature. In Naples, a kilometre from the sea, a grower saw his tropical cycads, including a Cycas thouarsii raised from seed, spend their first winter outdoors without protection in 2012–2013, with scorched leaves and a late recovery producing small leaves; on the west coast of Sicily the same grower kept them outdoors without problems (forum Tropicamente). The Jardin zoologique tropical at La Londe-les-Maures, in the Var, has published no observation on the species.

In Australia, the census of the Royal Botanic Gardens Victoria places four plants in outdoor beds at Melbourne Gardens (Magnolia Bed and Upper Fern Gully Bed), one of them recorded as planted in October 2013. This suggests that the species can live in the open in Melbourne’s mild climate, at least in sheltered beds; the census says nothing about any winter damage. In Sydney, the Royal Botanic Garden grows seven plants in numbered garden beds.

Container cultivation

In the United Kingdom and other cool regions it is a plant for a pot kept in a bright, frost-free glasshouse or conservatory over winter. French growers advise a very free-draining compost, warmth, regular watering in summer and little water in winter; a gardener in the Lot, in south-western France, keeps it in a pot without risking it in the ground (forum Fous de palmiers, 2013). Its large leaves, up to 3 m long, make it a big plant for a conservatory once mature.

In cultivation in the UK, US and Australia

In short: widely grown in botanic gardens in the United States and Australia, under glass in the United Kingdom. A garden listed in the BGCI PlantSearch database (consulted in October 2026) has declared the species at some point, which does not prove that a living plant is there today. Remember that many plants labelled Cycas circinalis may belong to this species.

  • United Kingdom: the Royal Botanic Gardens, Kew, and Glasgow Botanic Gardens declare the species in BGCI PlantSearch, as does Kew’s Millennium Seed Bank; in the British climate these plants can only be under glass.
  • United States: the online catalogue of Montgomery Botanical Center, in Coral Gables, Florida, lists nine accessions under this name, including accessions numbered from 1992 and 1995; the record carries a database remark giving another accepted name, which should be treated with caution. Fairchild Tropical Botanic Garden lists one old accession in its catalogue. In BGCI PlantSearch the species is also declared by the Huntington, Ganna Walska Lotusland, San Diego Botanic Garden, San Diego Zoo and Safari Park, the Missouri Botanical Garden, the University of California Botanical Garden at Berkeley, the New York Botanical Garden, Marie Selby Botanical Gardens, the National Tropical Botanical Garden and the University of Hawaii at Hilo, among others.
  • Australia: the Garden Explorer of the Royal Botanic Garden Sydney (updated on 1 October 2026) lists seven plants from accessions of 1990, 1991, 1997 and 2015, five of them in beds 102a and 102j; the census of the Royal Botanic Gardens Victoria lists four plants in outdoor beds at Melbourne; Brisbane Botanic Gardens Mount Coot-tha, the Botanic Garden of Adelaide, the Cairns Botanic Gardens and James Cook University in Townsville declare it in BGCI PlantSearch.

No first-hand report from a private grower in the United Kingdom, the United States or Australia has been published.

Propagation

Cycas thouarsii is propagated from seed; a male and a female plant are needed. The very large seeds take two years to ripen on the plant (Lindstrom, Hill and Stanberg 2009). A grower based in Poland reported on the French forum Fous de palmiers in 2008 that his “enormous” seeds germinated at about 25 °C (77 °F). Seeds are exempt from CITES under annotation #4. Since the seeds of this species float because of their spongy layer, flotation cannot be used as a test of seed viability.

Pests and diseases

The University of Florida has recorded the Asian cycad scale, Aulacaspis yasumatsui, on Cycas thouarsii in Miami-Dade County (Weissling, Howard and Hamon, fact sheet EENY-096). The cycad blue butterfly, Chilades pandava, attacks it on Réunion and Mauritius. As with all Cycas, waterlogged compost leads to root rot.

Cold hardiness

The published data are gardeners’ reports, often on plants sold as Cycas circinalis; they agree that the species tolerates only brief, light frosts.

European experience

These Mediterranean reports are the best guide available for comparable climates. A specialist nursery summed up in 2019, on the French forum Fous de palmiers, that the species tolerates only short frosts, and that if the frost lasts the foliage is burnt. A grower in Fuveau (Bouches-du-Rhône, France) reported in December 2019 that the leaves of his in-ground “Cycas circinalis” were burnt at 0 °C (32 °F); in Carcassonne (Aude, France), another lost 99% of the foliage at −1 °C (30.2 °F) (forum Au jardin). On the Côte Bleue, a young plant in the ground came through the winter of 2013–2014 intact, without any sub-zero temperature.

In Italy, a grower in Sabaudia (Lazio) reports on the forum Tropicamente that a young plant in the ground was almost entirely scorched at −2 to −3 °C (28.4 to 26.6 °F) without protection in 2009, and then produced only four leaves. In Pedara (province of Catania, Sicily), on the southern slope of Etna, a gardener wrote a month after two nights at −5 °C (23 °F) and −3 °C (26.6 °F), in February 2008, that among his in-ground cycads only the Cycas thouarsii would probably not survive, although the wording of his message is ambiguous. These figures are single observations, not tested limits.

United Kingdom, United States and Australia

No first-hand report with a temperature could be read for these countries. In the United Kingdom, nothing suggests that the species can be grown outdoors. In the United States, it is held mainly by gardens in southern Florida, coastal California and Hawaii, whose catalogues do not say whether the plants are in the open and publish no cold observations. In Australia, the plants in the garden beds of Melbourne and Sydney show that it can grow in the open in these cities, without any data on cold damage.

Toxicity and precautions

No toxicity analysis specific to Cycas thouarsii is documented, but the risk is well documented in the genus: Cycas tissues, and the seeds above all, contain cycasin, which is converted during digestion into methylazoxymethanol, toxic to the liver and nervous system, along with a neurotoxic amino acid, BMAA. The ASPCA lists the sago palm (Cycas revoluta) as poisonous to dogs, cats and horses. The big red seeds of Cycas thouarsii catch the eye: keep them out of reach of children and pets, handle them with gloves, and if any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

According to de Laubenfels and Adema (1998), Cycas thouarsii is still grown locally in Madagascar as a food plant; they see in this a possible explanation of its range, through transport by people. The published sources do not say which part is eaten or how it is prepared. As with other cycads, any consumption requires lengthy detoxification, never to be attempted at home.

Frequently asked questions

Is the “Cycas circinalis” sold in my garden centre a Cycas thouarsii?

Very probably. According to a specialist nursery, the tropical cycads sold in European garden centres as Cycas circinalis are Cycas thouarsii.

How can Cycas thouarsii be recognised?

By its big red seeds, 5 to 6 cm long, which float, and by its male cones whose scales end in a short hooked point. Its flat leaves carry 60 to 120 pairs of leaflets 8 to 13 mm wide.

Where does it come from?

From eastern Madagascar, the Comoros and the coasts of Kenya and Tanzania. It is the only African Cycas.

How does it differ from Cycas rumphii and Cycas seemannii?

These two species from Indonesia and the Pacific have microsporophylls almost without a point (5 mm at most); Cycas rumphii has crested seeds and broader leaflets, and Cycas seemannii a petiole with few spines.

Can it take frost?

Poorly. The foliage burns from 0 to −1 °C (32 to 30.2 °F) and almost entirely at about −2 to −3 °C (28.4 to 26.6 °F); one plant was probably lost after −5 °C (23 °F) in Sicily. Only the mildest coastal gardens allow an outdoor trial.

Can it be grown outdoors in the UK?

No. Grow it in a pot and keep it in a bright, frost-free glasshouse or conservatory over winter.

Does it grow fast?

Yes, for a cycad, according to growers. It is even crossed with slow-growing Australian cycads to speed up their growth.

Is it poisonous?

It must be assumed so. It has not been analysed, but all Cycas studied contain dangerous toxins, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Brown, R. (1810). Prodromus Florae Novae Hollandiae et Insulae Van-Diemen: 347. London. [Original publication according to The World List of Cycads.]
  • Aubert du Petit-Thouars, L.-M. (1804). Histoire des végétaux recueillis dans les îles australes d’Afrique: 2, t. 1–11. Paris. [Illustrations under the name Cycas circinalis; cited after de Laubenfels and Adema 1998.]
  • Stapf, O. (1916). Cycas Thouarsii. Bulletin of Miscellaneous Information, Kew 1916: 1–8. [Cited after The World List of Cycads and Lindstrom and Hill 2007.]
  • Vorster, P. & Vorster, E. (1986). Focus on Cycas thouarsii. Encephalartos 6: 3–10. [Cited after The World List of Cycads.]
  • Hill, K.D. (1994). The Cycas rumphii complex (Cycadaceae) in New Guinea and the western Pacific. Australian Systematic Botany 7(6): 543–567. doi:10.1071/SB9940543 [Subsection Rumphiae.]
  • de Laubenfels, D.J. & Adema, F. (1998). A taxonomic revision of the genera Cycas and Epicycas gen. nov. (Cycadaceae). Blumea 43(2): 351–400. [Description, synonymy, subgenus Cycas, range including Sri Lanka and the Zambezi delta, food use in Madagascar.]
  • Lindstrom, A.J. & Hill, K.D. (2007). The genus Cycas (Cycadaceae) in India. Telopea 11(4): 463–488. doi:10.7751/telopea20075745 [Cycas zeylanica separated from Cycas thouarsii; characters of Cycas circinalis.]
  • Lindstrom, A.J., Hill, K.D. & Stanberg, L.C. (2009). The genus Cycas (Cycadaceae) in Indonesia. Telopea 12(3): 385–418. doi:10.7751/telopea20095826 [Subsection Rumphiae, two-year seed ripening.]
  • Bösenberg, J.D. (2024). Cycas thouarsii. The IUCN Red List of Threatened Species 2024: e.T41940A69827688. doi:10.2305/IUCN.UK.2024-1.RLTS.T41940A69827688.en [Current assessment (LC); reference checked on Crossref and GBIF.]
  • Golding, J. & Hurter, J. (2010). Cycas thouarsii. The IUCN Red List of Threatened Species 2010: e.T41940A10606292. doi:10.2305/IUCN.UK.2010-3.RLTS.T41940A10606292.en [Previous assessment; reference checked on Crossref.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Etymology; used through The World List of Cycads.]
  • Calonje, M., Stevenson, D.W. & Osborne, R. (2026). The World List of Cycads, version 2026.08.15. Montgomery Botanical Center, Coral Gables. doi:10.5281/zenodo.21958524 [Reference checklist.]