Cycas falcata

Cycas falcata is a cycad from the island of Sulawesi, in Indonesia, known from two localities in the south-east of the main island and from the island of Kabaena, where it grows inland on limestone or serpentinite. Described in 1999 by Ken Hill, this member of the genus Cycas takes its name from its narrow leaflets, often curved like a sickle. It belongs to the Cycas rumphii group, but stands apart from it in its keeled leaves, small seeds and megasporophylls with long lateral spines. The IUCN lists it as Vulnerable (2022).

Key facts about Cycas falcata

  • Accepted name: Cycas falcata K.D.Hill (1999), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: no synonym; plants previously included in Cycas riuminiana in the broad sense of de Laubenfels and Adema (1998)
  • Family: Cycadaceae, order Cycadales
  • Common names: no common name attested, in English or any other language
  • Natural range: Indonesia, Sulawesi (South Sulawesi and South-East Sulawesi provinces), including the island of Kabaena
  • IUCN status: Vulnerable (VU, criteria B1ab(iii,v)), 2022 assessment, confirmed by the Red List data relayed by GBIF
  • CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: no data (see Cold hardiness)
  • Light and soil: from full sun to deep shade, from closed forest to low, grassy tree savanna, on limestone or serpentinite
  • Habit and adult size: trunk up to 5 m tall and 12 to 30 cm across; leaves 1.8 to 3 m long
  • In the UK, US and Australia: no garden record found
  • Toxicity: no data for the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas falcata

Cycas falcata can be recognised by its narrow, often strongly curved leaflets on slightly keeled leaves, and by its megasporophylls (the fertile leaves of female plants), whose blade carries 16 to 28 long, sharp lateral spines. These characters are unusual in its group, where the leaves are flat and the megasporophylls barely toothed. In detail, after the revision by Lindström, Hill and Stanberg (2009):

  • Trunk: upright, single or sometimes branched two or three times at the base, up to 5 m tall and 12 to 30 cm across.
  • Leaves: 180 to 300 cm long, olive green, glossy, slightly keeled (leaflets held opposite at about 150°), with 100 to 200 leaflets; rachis ending in a pair of leaflets or a short spine; petiole 27 to 62 cm, spiny over 80 to 100% of its length.
  • Median leaflets: often strongly sickle-shaped, 17 to 30 cm long and 7.5 to 13 mm wide, inserted at 60 to 70°, spaced 11 to 17 mm apart, with slightly recurved margins and a tapering tip; midrib green, strongly raised above.
  • Cataphylls (the scale leaves protecting the crown): broadly triangular, soft, 4 to 7 cm long, with short, mid-brown down.
  • Male cones: not seen by the authors of the revision.
  • Megasporophylls: 19 to 27 cm long, with mid-brown felt, carrying 4 to 6 hairless ovules; blade narrowly triangular, 60 to 70 mm by 22 to 32 mm, with 16 to 28 more or less sharp lateral spines 7 to 12 mm long; apical spine 15 to 28 mm.
  • Seeds: flattened-ovoid, 42 to 46 mm by 25 to 34 mm; fleshy coat orange-yellow, not powdery, without a fibrous layer; thin inner spongy layer.

Hybrids

No hybrid is documented. Lindström, Hill and Stanberg (2009) do not rule out that the species itself is of hybrid origin, between a cycad of the Cycas rumphii group and a cycad with comb-like megasporophylls, but they stress that nothing can prove it.

Possible confusion

  • Cycas rumphii, found on the coasts of eastern Indonesia: flat leaves, megasporophylls without distinct lateral spines, larger, ridged seeds, coastal habitat.
  • Cycas edentata, a coastal cycad of western Indonesia and South-East Asia: flat, very glossy leaves, broader leaflets, megasporophylls almost without teeth.
  • Cycas macrocarpa (Thailand, Peninsular Malaysia) and Cycas riuminiana (Philippines), which also have deeply toothed megasporophylls, but no spongy layer in the seed and a fibrous seed coat.

Taxonomy

Cycas falcata is a name accepted by The World List of Cycads; POWO could not be consulted directly. Ken Hill described it in 1999 in the Kew Bulletin (volume 54, page 209), on a type collected on 7 August 1993 on Mount Katopi, on the island of Kabaena, 18 km north-west of Tangkeno (McDonald & Ismael 4184, holotype at Kew). De Laubenfels and Adema (1998) had included these Sulawesi plants in a broad and imprecise concept of Cycas riuminiana.

The spongy layer of the seed places it unambiguously in subsection Rumphiae of section Cycas, the Cycas rumphii group. Yet it departs from it in several respects: small seeds, megasporophylls with long lateral spines, keeled leaves and narrow, sickle-shaped leaflets. Lindström and colleagues (2009) see these as derived characters: a species from a mainly coastal, sea-dispersed group that has colonised inland habitats and unusual soils.

Etymology and history

The epithet falcata comes from the Latin falcatus, “sickle-shaped”, after the clearly curved leaflets. The specimens known to the revision were collected between 1978 and 1993, notably between Soroako and Wasuponda and on the southern shore of Lake Matano in 1979, and around the Opa Swamp in 1978; no history of introduction into cultivation is documented.

Common names

No common name is recorded for this species, in English, French or Indonesian, in the sources consulted.

In the wild

Cycas falcata is known from two localities on the main island of Sulawesi (South Sulawesi and South-East Sulawesi provinces) and from the island of Kabaena, off the south-east coast. It occupies varied habitats, from closed forest to low, grass-dominated tree savanna, in full sun as well as deep shade, on limestone or serpentinite. This inland habitat contrasts with that of the other species in its group, almost all of which grow near the coast. Its pollinator, phenology and seed dispersers are not documented; even the male cones had not been seen in 2009.

GBIF (consulted on 21 October 2026) holds 26 records under this name: the herbarium specimens of 1978, 1979 and 1993 from the localities above, three iNaturalist observations from South-East Sulawesi in 2014, and specimens from North Sulawesi (around Tinoor, collected in 1999, and undated sheets), well outside the range given by the revision; their identification has not been checked.

Conservation status and regulation

Cycas falcata is listed as Vulnerable (VU) by the IUCN, under criteria B1ab(iii,v) (small range, with declining habitat quality and number of mature individuals), in the assessment by John Donald Bösenberg published in version 2022-1 of the Red List; the Red List data relayed by GBIF confirm the category (consulted on 21 October 2026), but the Red List itself could not be consulted directly. In 2009, Lindström and colleagues considered it little threatened in the short term but vulnerable in the long term, and recommended Near Threatened, the official category then being Data Deficient (Donaldson 2003). They called for further fieldwork. The specific threats to its sites are not detailed in the sources consulted.

Like every species in the genus except Cycas beddomei, Cycas falcata is listed in CITES Appendix II, through the listing of the family Cycadaceae, included since 4 February 1977. The listing carries annotation #4 (CoP20 version, in force since 5 March 2026): seeds, pollen, seedlings or tissue cultures obtained in vitro and transported in sterile containers, and cut flowers of artificially propagated plants, are not subject to CITES, whereas international trade in the plants themselves requires an export permit. Australia, the United Kingdom and the United States 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. Species+, the official CITES database, names the species and confirms this status (search of 3 October 2026). This general information does not replace the official texts: check the rules in force before buying or exchanging plants, ask the seller for proof of origin and prefer plants raised from cultivated seed.

Growing Cycas falcata

In short: no growing advice or growing report has been published for this species, and it does not seem to be in the trade. What follows is drawn from its habitat.

Outdoor and in-ground cultivation

No planting in the open ground is documented. Its natural setting, an equatorial climate, limestone or serpentinite soils and light ranging from sun to shade, points to a plant for tropical gardens, on a mineral, free-draining soil; this is a deduction from its habitat, not a growing result.

Container cultivation

In cool climates it could only be grown in a heated glasshouse, in a mineral, free-draining compost. No growing report was found on the French forum Fous de palmiers or the Italian forum Tropicamente, and the Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published no observation on this species.

In cultivation in the UK, US and Australia

No record of Cycas falcata was found in BGCI PlantSearch, in the online catalogues of Montgomery Botanical Center (Florida), the Royal Botanic Garden Sydney and the Australian Botanic Garden Mount Annan, or in the inventory of cycads in British, American and Australian gardens compiled for this site (searches of 21 October 2026). No report from an English-speaking grower could be read; PalmTalk and Dave’s Garden could not be consulted.

Propagation

The plant is dioecious: a male and a female plant are needed for fertile seed. No germination data specific to the species have been published. Seeds are exempt from CITES under annotation #4; ask for seed from cultivated plants.

Pests and diseases

No pest or disease specific to the species is documented. Cycad scales, including the Asian cycad scale, Aulacaspis yasumatsui, can affect all cultivated species.

Cold hardiness

No cold-tolerance data exist for Cycas falcata. Its range lies a few degrees south of the equator, and nothing suggests it can survive frost.

European experience

No growing result has been published in Europe, in the open ground or in a pot. Searches of the French forum Fous de palmiers and the Italian forum Tropicamente found no cold report for this species, and no dated frost event concerns it.

United Kingdom, United States and Australia

No cold reading or dated growing report was found, either on forums or from botanic gardens. No USDA zone can be given.

Toxicity and precautions

No toxicity analysis specific to Cycas falcata has been found. The risk is, however, 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. Until proven otherwise, treat the plant as poisonous: keep seeds and leaves out of reach of children and pets, and wear gloves to clean the seeds. If any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

No use is documented for this species.

Frequently asked questions

What does falcata mean?

“Sickle-shaped” in Latin: the name describes the narrow, curved leaflets, the most visible character of the species.

Where does it grow?

On Sulawesi, in Indonesia: in two localities in the south-east of the main island and on the island of Kabaena, away from the coast, on limestone or serpentinite.

Is it related to Cycas rumphii?

Yes, through the seed, which has a spongy layer like that of Cycas rumphii. But its keeled leaves, sickle-shaped leaflets and spiny megasporophylls clearly set it apart.

Is it endangered?

Yes. The IUCN has listed it as Vulnerable since 2022, because of its very small range and the decline of its habitat.

Can it be grown outdoors in the UK?

Almost certainly not. No cold data exist, and it is a plant of an equatorial climate: in the UK it would need a heated glasshouse.

Is it poisonous?

It must be assumed so. No analysis exists for the species, but all the cycads studied contain serious toxins, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Hill, K.D. (1999). Cycas falcata (Cycadaceae), a new species from Sulawesi, Indonesia. Kew Bulletin 54(1): 209 ff. doi:10.2307/4111041 [Original description; not consulted directly (JSTOR), title checked on Crossref.]
  • Lindström, A.J., Hill, K.D. & Stanberg, L.C. (2009). The genus Cycas (Cycadaceae) in Indonesia. Telopea 12(3): 385–418. doi:10.7751/telopea20095826 [Description (pp. 397–400), range, habitat, status; full text consulted.]
  • Lindström, A.J., Hill, K.D. & Stanberg, L.C. (2008). The genus Cycas (Cycadaceae) in The Philippines. Telopea 12(1): 119–145. doi:10.7751/telopea20085805 [Treatment of Cycas riuminiana by de Laubenfels and Adema; full text consulted.]
  • Laubenfels, D.J. de & Adema, F. (1998). A taxonomic revision of the genera Cycas and Epicycas gen. nov. (Cycadaceae). Blumea 43(2): 351–400. [Very broad species concepts; not consulted directly, cited after The World List of Cycads and Lindström et al.]
  • Bösenberg, J.D. (2022). Cycas falcata. The IUCN Red List of Threatened Species: e.T42092A68900953. doi:10.2305/IUCN.UK.2022-1.RLTS.T42092A68900953.en [Current assessment (VU); reference checked on Crossref, category relayed by GBIF; Red List page not consulted (access blocked).]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Source of the etymologies given by The World List of Cycads; not consulted directly.]
  • 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; consulted directly.]