Cycas condaoensis

Cycas condaoensis is a cycad endemic to the Côn Đảo archipelago, a group of islands off the southern coast of Vietnam that belongs to Bà Rịa-Vũng Tàu province. This species of the genus Cycas has an unusual history: its type specimen was collected in September 1877 by the French botanist Louis Pierre on the island then called Poulo Condor, yet the species was not described until 2004, by Ken Hill and Si Lin Yang. Unusually for a cycad with such a small range, the IUCN lists it as Least Concern. Its characters remain poorly known for lack of accessible sources, and this page keeps to what could be checked.

Key facts about Cycas condaoensis

  • Accepted name: Cycas condaoensis K.D.Hill & S.L.Yang (2004), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: no known synonym
  • Family: Cycadaceae, order Cycadales
  • Common names: no English or Vietnamese name attested
  • Natural range: Vietnam, Côn Đảo archipelago (Bà Rịa-Vũng Tàu province)
  • IUCN status: Least Concern (LC), reassessment by J. D. Bösenberg (Red List version 2023-1), LC according to GBIF; earlier assessment by H. T. Nguyễn (2010)
  • CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: no data; a tropical island species, to be kept frost-free (see Cold hardiness)
  • Light and soil: not documented in the accessible sources
  • Habit and adult size: not documented in the accessible sources (original description not consulted)
  • In the UK, US and Australia: Montgomery Botanical Center (Florida), one accession; no record in the UK or Australia
  • Toxicity: not studied for the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas condaoensis

The surest clue is its origin: it is the Cycas described from the Côn Đảo islands. The original description, published in 2004 in the revision of the Cycas of Vietnam by Hill, Nguyễn and Lộc (The Botanical Review, pages 178–179, figure 14), is behind a paywall and could not be read; the IUCN assessment and the Cycad Pages of the Royal Botanic Garden Sydney, now offline, were not accessible either. This page therefore gives no measurements: the figures that circulate online for the trunk, leaves and cones come from secondary summaries that cannot be checked against the original source.

Like all Cycas, it is dioecious: male plants bear a cone of microsporophylls, female plants carry their seeds on leaf-like megasporophylls, and the pinnate leaves, whose leaflets each have a single midrib, unfurl like a crozier. If, as Hill (2004) indicates, the species belongs to section Indosinenses, it should share the characters of that section: firm male cones, hairless ovules, a deeply comb-like megasporophyll blade and a layer of fibrous tissue in the fleshy seed coat (definition of the section by Hill 2008). This is an inference from the classification, not a description of the species. Older online accounts attributed to the section a “fibrous, smooth sclerotesta”: Hill places the fibrous layer in the sarcotesta, the fleshy coat, not in the hard shell.

Hybrids

No natural or garden hybrid is documented in the sources consulted.

Possible confusion

In the wild, its island origin is enough to identify it. In cultivation, however, it could be confused with the other species of section Indosinenses from mainland South-East Asia. According to Hill’s 2004 analysis, which could not be consulted directly, the species sits close to Cycas siamensis, in a group that also includes Cycas pectinata, Cycas clivicola, Cycas lindstromii and Cycas pranburiensis. Cycas lindstromii and Cycas pachypoda are its nearest neighbours geographically, on the mainland of southern Vietnam. Without a provenance label, telling them apart requires the original description.

Taxonomy

Cycas condaoensis is accepted by The World List of Cycads; POWO could not be consulted directly. Ken Hill and Si Lin Yang described it in the revision “The genus Cycas (Cycadaceae) in Vietnam” by K. D. Hill, T. H. Nguyễn and P. K. Lộc, The Botanical Review 70(2): 178–179, figure 14 (2004). The type is an old collection: Louis Pierre, no. 1722, from Poulo Condor (Côn Đảo), September 1877; the holotype is at Kew (K), with isotypes at the Arnold Arboretum (A), in Leiden (L) and in New York (NY). The International Plant Names Index records the name under identifier 60436316-2.

In Ken Hill’s classification, the species belongs to section Indosinenses, which Hill (2008) defines by firm or woody male cones, hairless ovules, a large, deeply comb-like megasporophyll blade and a layer of fibrous tissue in the sarcotesta. Its placement in this section comes from the morphological and molecular analysis published by Hill in 2004 in the edited volume Cycad Classification: Concepts and Recommendations, which could not be consulted. DNA sequences (phytochrome P and rbcL genes) from a herbarium specimen held in Hanoi (HN) have been deposited in the genetic databases and are indexed by GBIF.

Etymology and history

The epithet condaoensis means “from Côn Đảo” and recalls that the species is endemic to this group of islands (Haynes 2022, as cited by The World List of Cycads). Its history is unusual: the specimen that serves as its type was collected in 1877 by Louis Pierre, who was then exploring the flora of Cochinchina, and it lay in herbaria for more than a century before being recognised as a distinct species in 2004. The World List of Cycads gives the collector only as “Pierre, L”; identifying him with the botanist Louis Pierre is obvious in this context, but the source does not say so. The sources consulted do not say under which name the specimen was filed before.

Common names

No English common name is attested, and the British nursery Trebrown knows of none. No Vietnamese name specific to the species has been found either.

In the wild

Cycas condaoensis is known only from the Côn Đảo archipelago, off the southern coast of Vietnam: The World List of Cycads gives Bà Rịa-Vũng Tàu province, to which the islands belong, and Species+ simply Vietnam. The archipelago, which contains Côn Đảo National Park, has the tropical monsoon climate of southern Vietnam; the sources consulted do not say which populations lie within the park.

The exact habitat (vegetation type, substrate, altitude) and the size of the populations could not be checked. The descriptions in circulation contradict each other: some speak of granite slopes and rocky outcrops, others of coastal sands near sea level, without citing a source. Likewise, the distances from the islands to the mainland given in some summaries have not been used, for lack of a source.

Conservation status and regulation

Cycas condaoensis is not considered threatened: the current IUCN Red List category, relayed by GBIF, is Least Concern (LC) (consulted on 21 October 2026). The World List of Cycads cites the assessment by H. T. Nguyễn published in 2010; a reassessment by J. D. Bösenberg was published in Red List version 2023-1 (reference checked on Crossref) and keeps the same category. The reasoning behind these assessments could not be read, and no source consulted explains the favourable status by protection in the national park, as some summaries do. It is an uncommon situation for a Cycas with such a small range.

Like every species in the genus except Cycas beddomei, Cycas condaoensis 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. This general information does not replace the official texts: check the rules in force before buying or exchanging plants, and ask for proof that the plant was raised in cultivation.

Growing Cycas condaoensis

In short: the species is rare in cultivation and no published account of its needs has been found. It is a plant for tropical gardens or a heated glasshouse.

Outdoor and in-ground cultivation

It is nonetheless present in a few large collections. Herbarium sheets prepared in 2011 from plants grown at the Nong Nooch Tropical Botanical Garden, at Pattaya in Thailand (accessions 79 B and 79 V), are held at the Natural History Museum in Vienna (W), and fruits from one of these plants are kept in the museum’s carpological collection (GBIF data). In the United States, Montgomery Botanical Center lists one accession (see below). Advice found online (full sun, poor soils, wind tolerance) was deduced from a habitat that is itself unverified and is not repeated here.

Container cultivation

For a tropical island species with a monsoon climate, pot culture in a heated glasshouse or conservatory, in a very free-draining substrate, is the only reasonable option in the United Kingdom and similar climates: this is general guidance for tropical Cycas, not a documented result for this species. In Mediterranean Europe, no grower has reported it: a search for the name on the French forum Fous de palmiers returns nothing, nor does the Italian forum Tropicamente, and the Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published nothing on the species.

In cultivation in the UK, US and Australia

  • United States: the online catalogue of Montgomery Botanical Center (Coral Gables, Florida) lists one accession, whose number dates from 2016; the garden also declares it in BGCI PlantSearch.
  • United Kingdom and Australia: no record in BGCI PlantSearch or in the online catalogues consulted (Royal Botanic Garden Sydney, Australian Botanic Garden Mount Annan, Royal Botanic Gardens Victoria).

Elsewhere, BGCI lists the Palmengarten in Frankfurt and Prague Botanical Garden. The British nursery Trebrown lists the name. No report from a private grower in the UK, US or Australia could be read; PalmTalk and Dave’s Garden could not be consulted.

Propagation

Like all Cycas, Cycas condaoensis is dioecious and is raised from seed: 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; given the island origin and rarity of the species, only seed of documented legal origin is acceptable.

Pests and diseases

No pest or disease specific to the species is documented. Like all Cycas, it is exposed to the Asian cycad scale, Aulacaspis yasumatsui, and to root rot in waterlogged substrate. The cycad blue butterfly, mealybugs and spider mites mentioned in some generic accounts have not been recorded on this species in the sources consulted.

Cold hardiness

No cold-tolerance data exist for Cycas condaoensis. It lives on tropical islands in southern Vietnam where frost is unknown, and nothing shows that it can take any. The British nursery Trebrown gives it USDA zone 9b, an average annual minimum of −3.9 to −1.1 °C (25 to 30 °F), as for many other Cycas in its catalogue: this is a commercial rating with no growing observation behind it.

European experience

No growing result has been published in Europe, in the open ground or in a pot, and no dated frost episode concerns the species. In the absence of data, grow it in a pot, frost-free.

United Kingdom, United States and Australia

No cold reading and no growing report were found. The only documented plantings are in tropical or near-tropical settings (Nong Nooch in Thailand; Montgomery in South Florida). No USDA zone can be given without a documented trial.

Toxicity and precautions

No toxicity analysis specific to Cycas condaoensis 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. North Carolina State University notes that cycasin is present in all parts of the plant, and the ASPCA lists the sago palm (Cycas revoluta) as poisonous to dogs, cats and horses, with vomiting, sometimes bloody diarrhoea, jaundice and liver damage that can be fatal. Until proven otherwise, treat the plant as poisonous: wear gloves to handle the seeds and their fleshy coat, pick up fallen seeds, and keep plants and seeds out of reach of children and pets. If any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

No traditional use specific to Cycas condaoensis is documented in the sources consulted. Given the toxins of the genus, no part of the plant should be eaten.

Frequently asked questions

Where does Cycas condaoensis grow?

Only in the Côn Đảo archipelago, off the southern coast of Vietnam (Bà Rịa-Vũng Tàu province). Its exact habitat on the islands could not be checked.

What does “condaoensis” mean?

“From Côn Đảo”. The name recalls the islands to which the species is endemic.

When was it discovered?

Collected in 1877, described in 2004. Louis Pierre gathered the type specimen in September 1877, but Hill and Yang recognised and described the species only in 2004.

Is it endangered?

No, according to the IUCN: it is listed as Least Concern (assessments of 2010 and 2023), despite a range limited to a small archipelago. It remains subject to CITES (Appendix II) and, in the European Union, to Annex B.

Which group does it belong to?

To section Indosinenses, according to Ken Hill, close to Cycas siamensis, Cycas pectinata and Cycas clivicola. This placement rests on a 2004 analysis that could not be consulted.

Can it be grown outdoors in the UK?

No. It is a tropical island species with no documented cold tolerance; grow it in a pot under heated glass.

Is it poisonous?

It must be assumed so. It has not been studied, but all parts of Cycas are poisonous, especially the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Hill, K.D., Nguyễn, T.H. & Lộc, P.K. (2004). The genus Cycas (Cycadaceae) in Vietnam. The Botanical Review 70(2): 134–193. doi:10.1663/0006-8101(2004)070[0134:TGCCIV]2.0.CO;2 [Original description, pages 178–179, figure 14; text not consulted (paywalled), reference checked through The World List of Cycads.]
  • Hill, K.D. (2004). Character evolution, species recognition and classification concepts in the Cycadaceae. In T. Walters & R. Osborne (eds), Cycad Classification: Concepts and Recommendations: 23–44. CABI Publishing, Wallingford. [Morphological and molecular analysis, placement in section Indosinenses; text not consulted, information given with this reservation.]
  • Hill, K.D. (2008). The genus Cycas (Cycadaceae) in China. Telopea 12(1): 71–118. doi:10.7751/telopea20085804 [Definition of section Indosinenses; full text consulted.]
  • Nguyễn, H.T. (2010). Cycas condaoensis. The IUCN Red List of Threatened Species 2010: e.T42050A10638748. doi:10.2305/IUCN.UK.2010-3.RLTS.T42050A10638748.en [LC assessment cited by The World List of Cycads; reference checked on Crossref, page not consulted.]
  • Bösenberg, J.D. (2023). Cycas condaoensis. The IUCN Red List of Threatened Species 2023: e.T42050A67340556. doi:10.2305/IUCN.UK.2023-1.RLTS.T42050A67340556.en [Current assessment, LC; reference checked on Crossref, category relayed by GBIF; 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 [Etymology; cited 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; consulted directly.]