Cycas seemannii

Cycas seemannii is the cycad of the south-west Pacific: it grows mainly near the coasts of Fiji, Tonga, Vanuatu and New Caledonia, where it is also widely planted. A member of the group of coastal cycads with floating seeds in the genus Cycas, it was long attached to Cycas circinalis and then to Cycas rumphii, and one revision still places it in Cycas celebica. Listed as Vulnerable, it has great cultural importance in Vanuatu. A strictly tropical plant, it is rarely grown outside the tropics, where it needs a heated glasshouse.

Key facts about Cycas seemannii

  • Accepted name: Cycas seemannii A.Braun (1876), 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)
  • Former names: Cycas circinalis subsp. seemannii (A.Braun) J.Schust. (1932), Cycas rumphii var. seemannii (A.Braun) Parham (1948); included in Cycas celebica by de Laubenfels and Adema (1998)
  • Family: Cycadaceae, order Cycadales; subsection Rumphiae K.D.Hill
  • Common names: no established English name; logologo in Fijian (Species+); “Longolongo” on the labels of the Royal Botanic Garden Sydney
  • Natural range: Fiji, New Caledonia, Tonga, Vanuatu; Keppel (2009) also studied populations in the Torres Strait Islands
  • IUCN status: Vulnerable (VU A4cd), assessment by J. D. Bösenberg published in 2022
  • CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: no published measurement; a species of frost-free tropical maritime climates (see Cold hardiness)
  • Light and soil: in the wild, mainly coastal sites; in cultivation, warmth, bright light and a free-draining compost
  • Habit and adult size: trunk up to 15 m and 14 to 30 cm across, often branched, according to de Laubenfels and Adema (1998), who include other populations; leaves 1 to 3 m long
  • In the UK, US and Australia: more than a hundred plants at the Royal Botanic Garden Sydney, many of wild origin; eight accessions at Montgomery Botanical Center (Florida); Kew, Edinburgh and Glasgow in the UK (BGCI)
  • Toxicity: no analysis specific to the species; to be treated as poisonous, like all cycads (see Toxicity and precautions)

How to recognise Cycas seemannii

Cycas seemannii is a large cycad with flat leaves and a petiole with few or no spines, whose male cones have short-pointed scales and whose large seeds, with a small ridge, float thanks to a spongy layer (de Laubenfels and Adema 1998; Lindstrom, Hill and Stanberg 2009). Keppel (2009) stresses that the species is very variable: the characters he measured vary greatly from one population to another, with no link to genetic differences.

The only detailed description consulted is that of Cycas celebica by de Laubenfels and Adema (1998), which covers Cycas seemannii and Cycas micronesica. In it, the trunk reaches 15 m and 14 to 30 cm across, often branched. The leaves are 100 to 300 cm long and carry 65 to 150 leaflets on each side; the petiole, 25 to 60 cm long, has few or no spines. The leaflets are 15 to 32 cm long and 10 to 16 mm wide, and clearly tapering when they are more than 12 mm wide.

The male cones, egg-shaped, are 32 to 60 cm long and 8 to 15 cm across; each microsporophyll ends in a point 4 to 5 mm long. The megasporophylls carry 2 to 6 ovules and a triangular or elongated blade 35 to 60 mm long, with 7 to 14 teeth on each side and a point 7 to 30 mm long. The seeds, tawny, are 55 to 70 mm long and 45 to 60 mm wide. They take two years to ripen (Lindstrom, Hill and Stanberg 2009). According to Keppel (2001), female plants carry on average longer leaves with more leaflets than male plants.

Hybrids

No natural or documented garden hybrid of Cycas seemannii has been published.

Possible confusion

A name long merged into other species

Seemann first published the Fijian plant as Cycas circinalis (1865), before A. Braun described it in 1876. Schuster (1932) then ranked it as a subspecies of Cycas circinalis, and Parham (1948) as a variety of Cycas rumphii (de Laubenfels and Adema 1998). Yet Cycas circinalis, from India, has no floating seeds: that link has now been abandoned. In New Caledonia, a gardener at Tontouta reports on the French forum Fous de palmiers (2012) that the species is found “everywhere” on the island, and a specialist nurseryman corrected in 2011, in a thread about these plants, the name “Cycas circinalis” given to them.

Telling it from related species

  • Cycas rumphii, from eastern Indonesia: petiole often spiny along its whole length, broader leaflets (12 to 18 mm), seeds with a marked ridge (de Laubenfels and Adema 1998; Lindstrom, Hill and Stanberg 2009).
  • Cycas micronesica, from Guam and the Marianas: separated by Hill (1994) on the megasporophyll blade, elliptic rather than triangular, and fewer lateral teeth; de Laubenfels and Adema (1998) consider these characters unstable.
  • Cycas thouarsii, from East Africa and Madagascar: petiole spiny for most of its length, microsporophylls with a hooked point 5 to 8 mm long, red seeds (de Laubenfels and Adema 1998).
  • Cycas bougainvilleana, from Papua New Guinea: another species of the group described by Hill (1994), which de Laubenfels and Adema (1998) included in Cycas rumphii.

Taxonomy

A. Braun described Cycas seemannii in 1876 from Berthold Seemann’s collection no. 572, made in Fiji in 1860; a lectotype kept at Kew was designated by Smith (1979), with isotypes in London and Geneva (The World List of Cycads; de Laubenfels and Adema 1998). The World List of Cycads gives the place of publication as the Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin (1876: 114–115).

The revisions differ markedly. Hill (1994) accepts Cycas seemannii in his subsection Rumphiae and separates Cycas micronesica from it for the plants of the Marianas (from the abstract of the article and as cited by de Laubenfels and Adema). De Laubenfels and Adema (1998), who examined material from the Marianas, New Caledonia, Fiji and Tonga, found both extremes everywhere; they placed Cycas seemannii and Cycas micronesica in Cycas celebica Miq., which they distinguished from Cycas rumphii by its narrower leaflets and spineless petiole. Lindstrom, Hill and Stanberg (2009) then placed Cycas celebica in the synonymy of Cycas rumphii. The World List of Cycads, which this site follows, accepts Cycas seemannii and Cycas micronesica as separate species.

The group of cycads with floating seeds is subsection Rumphiae (Hill 1994; Lindstrom, Hill and Stanberg 2009), to which Cycas media does not belong.

Genetics supports the isolation of the populations: Keppel (2002) found low genetic diversity and strong differentiation between populations, and a second article published in 2002 in the Journal of Heredity concludes, in its very title, that they have long been isolated.

Etymology and history

The epithet honours Berthold Carl Seemann (1825–1871), a German naturalist and editor who made the type collection (Haynes 2022, after The World List of Cycads). Seemann had treated the plant as Cycas circinalis in his Flora Vitiensis (1865).

Common names

There is no established English name. Species+ gives the Fijian name logologo, and the Royal Botanic Garden Sydney labels its plants “Longolongo”. No published source confirms that the namele leaf on the flag and coat of arms of Vanuatu is that of this cycad.

In the wild

The World List of Cycads restricts Cycas seemannii to Fiji, New Caledonia, Tonga and Vanuatu. Keppel (2009) also studied populations in the Torres Strait Islands, between Australia and New Guinea; Species+ lists Australia. Keppel (2002) cautiously estimated the number of plants remaining in the wild at 17,000, more than half of them in Vanuatu.

The species occupies several types of habitat, but mainly coastal sites (Keppel 2001). It reproduces mostly by seed and by offsets; wind seems to be the main pollinating agent, and seed dispersal, apart from the ocean route, seems inefficient. It grows about 5 to 15 cm a year, and the sexes are roughly equal in number. The larvae of an unidentified moth mine its leaflets; they are themselves parasitised by at least two species of wasp (Keppel 2001).

Conservation status and regulation

The IUCN lists Cycas seemannii as Vulnerable (VU A4cd), in the assessment by J. D. Bösenberg published in 2022 (category checked on GBIF and The World List of Cycads). The previous assessment, by K. D. Hill, dates from 2010. Keppel (2002) had already recommended this listing: the population is declining, above all because of repeated fires, but also because of the loss of the plant’s cultural importance and the protection that came with it, the conversion of habitats to farming and urban development, and a low capacity to recolonise. On the most populated islands, such as Viti Levu (Fiji) or around Nuku’alofa (Tonga), the species would be locally Endangered or even Critically Endangered. Since the populations are genetically distinct, he recommends conserving them island by island.

Like the whole Cycadaceae family, the species has been listed in CITES Appendix II since 4 February 1977, with annotation #4 (CoP20 version, in force since 5 March 2026): seeds, pollen and seedlings in sterile containers are not covered by CITES. In the European Union it falls under Annex B of Regulation (EC) No 338/97 (annexes set by Regulation (EU) 2026/1383, in force since 29 June 2026). Check the regulations in force before any purchase or exchange, and prefer plants raised from seed in cultivation.

Growing Cycas seemannii

Keppel (2009) reports that Cycas seemannii is widely grown as an ornamental within its range. Outside the tropics it is rare, and no growing guide specific to the species has been published.

Outdoor and in-ground cultivation

In New Caledonia (Tontouta), a gardener who grows it in the ground finds only one fault with it: its slowness (Fous de palmiers forum, 2014). In the United States, the University of Florida has recorded it in Miami-Dade County, in southern Florida (see Pests and diseases). Outdoor planting can only be considered in frost-free tropical climates. Keppel’s measurements (5 to 15 cm a year in the wild) do not suggest a fast-growing plant.

Container cultivation

Elsewhere, it is a plant for a heated glasshouse or conservatory, in a container, with a very free-draining compost, bright light and warmth all year round: this is a deduction from its natural range. In the UK, the few gardens that list it grow it under glass.

In cultivation in the UK, US and Australia

  • United Kingdom: Kew, the Royal Botanic Garden Edinburgh and Glasgow Botanic Gardens declare it to BGCI PlantSearch; these are glasshouse plants.
  • United States: Montgomery Botanical Center lists eight accessions in its online catalogue; the Huntington, Lotusland, the San Diego Zoo, the UC Berkeley Botanical Garden and seven other gardens declare it to BGCI PlantSearch.
  • Australia: the online catalogue of the Royal Botanic Garden Sydney (consulted on 21 October 2026) lists 109 plants, many of them of wild origin, collected in Fiji, Tonga and Vanuatu (accessions of 1993), and others of garden origin, including one from New Caledonia; Brisbane Botanic Gardens and three other gardens declare it to BGCI PlantSearch.

A BGCI entry shows that a garden has listed the species at some point, not that a plant is alive today.

Propagation

Cycas seemannii is propagated from seed and, in the wild, by offsets (Keppel 2001). A male and a female plant are needed to obtain seed, which takes two years to ripen (Lindstrom, Hill and Stanberg 2009). No germination protocol specific to the species has been published. Seeds are exempt from CITES.

Pests and diseases

In the wild, the leaflets are mined by the larvae of an unidentified moth (Keppel 2001). In Florida, the University of Florida has recorded the Asian cycad scale, Aulacaspis yasumatsui, on Cycas seemannii in Miami-Dade County (Weissling, Howard and Hamon, fact sheet EENY-096). Like all cycads, it can rot if the compost stays wet in cool conditions.

Cold hardiness

No cold-hardiness measurement has been published for Cycas seemannii, and no outdoor growing report has been published outside the tropics. The species grows in frost-free tropical archipelagos and is grown in the ground in New Caledonia (USDA zone 11b according to the Tontouta gardener quoted above).

In Europe, no result in the ground has been published, either in France or in Italy, and the Jardin zoologique tropical at La Londe-les-Maures (Var) has published no observations on the species. In the UK, it is grown only under glass; in the United States, outdoor cultivation is documented only in southern Florida; in Australia, the Royal Botanic Garden Sydney grows it in its garden beds, but no frost data are documented. In practice, treat it as a frost-tender plant for a heated glasshouse outside the tropics.

Toxicity and precautions

No toxicity analysis specific to Cycas seemannii has been published, but all the Cycas species studied contain cycasin, which is converted in the body into methylazoxymethanol, toxic to the liver and nervous system, along with a neurotoxic amino acid, BMAA, especially in the seeds (NC State Extension; ASPCA). The ASPCA lists Cycas revoluta as toxic to dogs, cats and horses. Treat the plant as poisonous: keep seeds out of reach of children and pets, wear gloves to handle them and, if any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

Keppel (2009) stresses the great cultural importance of the plant in Vanuatu, and the use of its seeds as a source of starch. He is concerned about the consequences of the loss of this cultural importance, which once ensured the plant’s protection (Keppel 2002). The published sources do not describe the preparations; as with other cycads, any consumption requires lengthy detoxification, never to be attempted at home.

Frequently asked questions

Where does Cycas seemannii grow?

In Fiji, Tonga, Vanuatu and New Caledonia, mainly near the coast; more than half of the wild plants are thought to be in Vanuatu.

How does it differ from Cycas rumphii?

By its petiole with few or no spines, its narrower leaflets and its weaker seed ridge, according to de Laubenfels and Adema (1998). But the species is very variable.

Is it a separate species?

Yes for The World List of Cycads, which this site follows, and for Hill (1994). De Laubenfels and Adema (1998) placed it in Cycas celebica, now included in Cycas rumphii.

Is it endangered?

Yes, it is listed as Vulnerable (2022): repeated fires, loss of cultural importance and habitat conversion are reducing its populations, which have little genetic diversity.

Can I grow it outdoors in the UK or the United States?

Not in the UK, where it needs a heated glasshouse. In the United States, only in frost-free areas such as southern Florida, where it is recorded in Miami-Dade County.

Is it fast-growing?

No: about 5 to 15 cm of trunk a year in the wild (Keppel 2001), and a New Caledonian gardener finds it slow.

Is it poisonous?

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

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Braun, A. (1876). Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1876: 114–115. [Protologue; reference checked on The World List of Cycads.]
  • Seemann, B. (1865). Flora Vitiensis: 268. London. [Plant treated as Cycas circinalis; cited after de Laubenfels and Adema 1998.]
  • 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 [Cycas seemannii accepted, Cycas micronesica described.]
  • de Laubenfels, D.J. & Adema, F. (1998). A taxonomic revision of the genera Cycas and Epicycas gen. nov. (Cycadaceae). Blumea 43(2): 351–400. [Cycas seemannii and Cycas micronesica in Cycas celebica, description, lectotype.]
  • Keppel, G. (2001). Notes on the natural history of Cycas seemannii (Cycadaceae). The South Pacific Journal of Natural and Applied Sciences 19: 35–41. doi:10.1071/SP01007 [Growth, sex ratio, offsets, pollination, leaf miner.]
  • Keppel, G. (2002). Low genetic variation in a Pacific cycad: conservation concerns for Cycas seemannii (Cycadaceae). Oryx 36(1): 41–49. doi:10.1017/S0030605302000078 [Numbers, threats, status.]
  • Keppel, G. (2002). Evidence for long isolation among populations of a Pacific cycad: genetic diversity and differentiation in Cycas seemannii A.Br. (Cycadaceae). Journal of Heredity 93(2): 133–139. doi:10.1093/jhered/93.2.133 [Title and reference checked on Crossref (full author list not checked).]
  • Keppel, G. (2009). Morphological variation, an expanded description and ethnobotanical evaluation of Cycas seemannii A.Braun (Cycadaceae). The South Pacific Journal of Natural and Applied Sciences 27: 20–27. doi:10.1071/SP09004 [Variability, Torres Strait, uses.]
  • 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 maturation, Cycas celebica in synonymy of Cycas rumphii.]
  • Bösenberg, J.D. (2022). Cycas seemannii. The IUCN Red List of Threatened Species 2022: e.T42064A67759797. doi:10.2305/IUCN.UK.2022-1.RLTS.T42064A67759797.en [Current assessment (VU); reference checked on Crossref.]
  • Hill, K.D. (2010). Cycas seemannii. The IUCN Red List of Threatened Species 2010: e.T42064A10641249. doi:10.2305/IUCN.UK.2010-3.RLTS.T42064A10641249.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.]