Cycas sundaica

Cycas sundaica is a tree-like cycad of the Lesser Sunda Islands, in Indonesia, found from Sumbawa to Alor by way of Komodo, Rinca and Flores, where it grows in near-coastal and lowland forest. This species of the genus Cycas, described in 2009 by Anders Lindström and Ken Hill, bears a name that the Dutch botanist Miquel had written on a herbarium sheet but never published. Close to Cycas rumphii, it differs in the well-marked lateral spines of its megasporophylls. The IUCN lists it as Least Concern.

Key facts about Cycas sundaica

  • Accepted name: Cycas sundaica Miq. ex A.Lindstr. & K.D.Hill (2009), accepted by The World List of Cycads (version 2026.08.15) and by GBIF; the World Checklist of Vascular Plants (WCVP), on which POWO is based, also accepts it (consulted through GBIF on 31 October 2026)
  • Former names and synonyms: no synonym; “Cycas sundaica Miq.” was cited by Schuster (1932), as an unpublished name, in the synonymy of Cycas rumphii
  • Family: Cycadaceae, order Cycadales
  • Common names: none attested, in English, Indonesian or any other language
  • Natural range: Indonesia, Lesser Sunda Islands (West and East Nusa Tenggara provinces): Sumbawa, Komodo, Rinca, Flores, east to Alor
  • IUCN status: Least Concern (LC), assessment by L. Stanberg and A. Lindström published in Red List version 2023-1; LC according to 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: near-coastal and lowland forest; soil not documented
  • Habit and adult size: trunk up to 5 m, 20 to 35 cm across; leaves 1.2 to 2.75 m long
  • In the UK, US and Australia: no garden or nursery record found
  • Toxicity: no data specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas sundaica

By the distinct lateral spines of its megasporophylls and its flat leaves. In the key of Lindström, Hill and Stanberg (2009), Cycas sundaica belongs to the Indonesian Cycas whose seeds have a spongy layer, and it is separated from the others by these two characters; its leaflets are also, on average, narrower than those of related species. The description below is the original one.

  • Trunk: tree-like, up to 5 m tall and 20 to 35 cm in diameter.
  • Leaves: 120 to 275 cm long, bright green or deep green, flat in section, with 75 to 114 leaflets; orange to greyish down, shed as the leaf expands; rachis usually ending in a spine up to 13 mm long; petiole 30 to 67 cm (20 to 40% of the leaf), spiny along 10 to 100% of its length; basal leaflets not reduced to spines.
  • Median leaflets: 23 to 34 cm long and 9 to 15 mm wide, much paler below, narrowed to 3 to 5 mm at the base, set 13 to 23 mm apart; margins slightly recurved; tip sharp; midrib flat above, raised below.
  • Cataphylls (the scale leaves that protect the growing point): linear, pungent, up to 10 cm long.
  • Male cones: ovoid, about 16 to 30 cm long and 9 to 15 cm across; microsporophylls firm, 30 to 55 mm long, with an abruptly raised apical spine 12 to 20 mm long.
  • Megasporophylls: 30 to 42 cm long, with persistent down, carrying 2 to 8 hairless ovules; lance-shaped blade 30 to 80 mm long and 20 to 43 mm wide, shallowly comb-like or regularly toothed, with 4 to 30 pungent lateral spines 1 to 12 mm long; apical spine distinct, 3 to 7 mm wide at the base.
  • Seeds: ovoid, 45 to 55 mm long and 35 to 45 mm wide; fleshy coat (sarcotesta) orange, about 8 mm thick, without a fibrous layer; stony layer smooth; spongy layer present.

The published text gives the apical spine of the megasporophyll as “30–50 cm” long and the seeds as “35–45 cm” wide: these are obvious unit errors for millimetres. The length of the apical spine is therefore not repeated here.

Hybrids

No hybrid is documented for this species.

Possible confusion

  • Cycas rumphii, of the Moluccas, and Cycas edentata, a coastal cycad: the same floating seeds, but megasporophylls without distinct lateral spines and leaflets broader on average (Lindström et al. 2009).
  • Cycas falcata, of Sulawesi: also with distinct lateral spines, but with openly keeled leaves.
  • Cycas montana, of the mountains of Flores, and Cycas glauca, of Timor and Sumba: seeds without a spongy layer; Cycas glauca also has glaucous foliage.

Taxonomy

Cycas sundaica is a name accepted by The World List of Cycads and by GBIF; the World Checklist of Vascular Plants (WCVP), on which POWO is based, also accepts it (consulted through GBIF on 31 October 2026). It was described in 2009 in the revision of the Indonesian Cycas by Lindström, Hill and Stanberg (Telopea 12(3): 408–410, fig. 6), together with Cycas montana. The authors place it in section Cycas, subsection Rumphiae, the group of Cycas whose seeds contain a layer of spongy tissue. This layer makes the seeds float and is thought to help their dispersal by sea; according to the same authors, it would also explain the taxonomic complexity of the group, which ranges from Africa to Fiji and Tonga, where successive colonisations would have produced strong local variability.

The name has an unusual history. Miquel had written it on a herbarium sheet in Utrecht without ever publishing it; Schuster (1932) listed it in the synonymy of Cycas rumphii, which did not make it a valid name. Lindström and Hill took it up in 2009 and published it validly, hence the author citation “Miq. ex A.Lindstr. & K.D.Hill”. For the reader, older literature that treats all the floating-seeded cycads of the region as Cycas rumphii may include plants now referred to Cycas sundaica.

Etymology and history

The epithet refers to the Sunda Islands, to which the species is entirely confined (Lindström et al. 2009; Haynes 2022).

The type was collected on 29 April 2000 by Anders Lindström on the island of Flores, at the foot of the Inerie volcano, along the Eku Ture river, near the village of Bidhu, at 326 m (Lindström 255; holotype at Bogor, isotype at the University of British Columbia, Vancouver). Older collections exist: Endeh, on Flores (1927), Alor (1938–1939) and Pota, in western Flores (1980). No history of introduction into cultivation is documented.

Common names

No common name is attested for this species, in English, Indonesian or any other language.

In the wild

Cycas sundaica lives in near-coastal and lowland forest on Sumbawa, Komodo, Rinca and Flores, east to Alor (Lindström et al. 2009). The specimens cited were collected between 20 and 750 m above sea level. The 2009 text says the species is confined to East Nusa Tenggara, but Sumbawa belongs to West Nusa Tenggara; The World List of Cycads accordingly cites both provinces. Soil, pollination and phenology are not documented.

Conservation status and regulation

The IUCN lists Cycas sundaica as Least Concern (LC). The World List of Cycads does not give the year of the assessment: according to Crossref, it is the assessment by L. Stanberg and A. Lindström dated 2020 and published in version 2023-1 of the Red List, and the Red List data relayed by GBIF confirm the category (consulted on 24 October 2026). In 2009 the authors of the species already proposed this status: locally abundant, the species occurs in the reserves set aside for the Komodo dragon and is not considered to be at immediate risk.

Like every species in the genus except Cycas beddomei, Cycas sundaica falls under CITES Appendix II, where the family Cycadaceae has been included since 4 February 1977. Annotation #4 (CoP20 version, in force since 5 March 2026) exempts seeds, pollen, seedlings and tissue cultures obtained in vitro and transported in sterile containers, and cut flowers of artificially propagated plants; international trade in the plants themselves requires an export permit. The United Kingdom, the United States and Australia apply CITES through their own legislation; in the European Union the species is in Annex B of Regulation (EC) No 338/97, as set by Commission Regulation (EU) 2026/1383, applicable since 29 June 2026. Species+, the official CITES database, lists the species under its own name and confirms this status. This information was checked in October 2026 and does not replace the official texts: check the rules in force, ask for proof of origin and prefer plants raised from seed in cultivation.

Growing Cycas sundaica

In short: no institution consulted documents it in cultivation and no grower’s report has been published.

Outdoor and in-ground cultivation

The points below are deductions from its habitat, not documented results. A cycad of tropical lowland forest, on islands with a marked dry season, it is likely to need warmth, good light and a free-draining soil. Outdoors, only frost-free tropical climates can be considered, such as southern Florida or northern Australia; no garden in these regions has published results.

Container cultivation

In the United Kingdom and other temperate regions, the only realistic option would be a pot in a heated glasshouse, in a mineral, free-draining mix and in full light; its large leaves, up to 2.75 m long, call for a large house. No European experience exists.

In cultivation in the UK, US and Australia

In short: no record. The species does not appear in the BGCI PlantSearch database or in the online catalogue of Montgomery Botanical Center (both consulted on 24 October 2026), nor in the online catalogues of British, American and Australian gardens (October 2026). Plants grown under the name Cycas rumphii may include material of other floating-seeded species, but no source links any of them to Cycas sundaica. No report from a private grower is documented.

Propagation

The plant is dioecious: seed requires a male and a female plant. No germination data specific to the species have been published. Seeds are exempt from CITES under annotation #4; look for seed from cultivated plants, of documented, legal origin.

Pests and diseases

No disease or pest specific to the species is documented. In cultivation, as with any Cycas, scales such as Aulacaspis yasumatsui can attack it, and overwatering or poor drainage rots the trunk and roots.

Cold hardiness

No cold-tolerance data exist for Cycas sundaica. The Lesser Sunda Islands have a tropical climate without frost, and nothing suggests that the plant can take frost.

Mediterranean and European experience

No cultivation result has been published in Europe, in the open ground or in a pot, and no dated frost episode concerns this species.

United Kingdom, United States and Australia

No cold reading is documented in any country, and no nursery gives a hardiness rating. Treat it as a frost-tender plant: a heated glasshouse in the UK, frost-free tropical gardens elsewhere.

Toxicity and precautions

No toxicity analysis specific to Cycas sundaica has been published, 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. In the absence of evidence to the contrary, treat the plant as poisonous: keep seeds and leaves out of reach of children and animals and wear gloves to clean seeds. If any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

No use of this species is documented.

Frequently asked questions

Where does the name sundaica come from?

From the Sunda Islands, in Indonesia, to which the species is endemic.

Where does Cycas sundaica grow?

On Sumbawa, Komodo, Rinca, Flores and Alor, in near-coastal and lowland forest.

Does it grow on Java?

No. The World List of Cycads and its original description confine it to the Lesser Sunda Islands.

How do I tell it from Cycas rumphii?

By the distinct lateral spines of the megasporophylls and the leaflets, narrower on average.

Do its seeds float?

Yes, according to its description: they contain a spongy layer, like those of the other Cycas of subsection Rumphiae.

Is it endangered?

No. The IUCN lists it as Least Concern, and the species occurs in the protected areas of Komodo.

Is it hardy in the UK?

Almost certainly not. No cold data exist and its range is tropical: grow it in a heated glasshouse.

Is it poisonous?

It should be assumed so. No analysis exists for this species, but all the Cycas studied contain dangerous toxins, above all in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • 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 [Original description (pp. 408–410, fig. 6), key, subsection Rumphiae, specimens, proposed status.]
  • Schuster, J. (1932). Cycadaceae. In: Engler, A. (ed.), Das Pflanzenreich IV.1 (Heft 99). Leipzig. [Cites Miquel’s name in synonymy; cited from Lindström et al. (2009).]
  • Stanberg, L. & Lindström, A. (2023). Cycas sundaica. The IUCN Red List of Threatened Species: e.T187821A1827396. doi:10.2305/IUCN.UK.2023-1.RLTS.T187821A1827396.en [Assessment dated 2020; reference found on Crossref, LC category relayed by GBIF.]
  • 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.]
  • 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.]