Cycas pachypoda

Cycas pachypoda is a cycad endemic to southern Vietnam, known only from the coastal provinces of Bình Thuận and Ninh Thuận. This species of the genus Cycas was described in 2004 by the Australian botanist Ken Hill, who named it after the large, strongly swollen base of its trunk. It is one of the most threatened cycads in the country: the IUCN lists it as Critically Endangered. Its full description, published in a subscription journal, could not be consulted, so this page is limited to what verifiable sources allow us to state.

Key facts about Cycas pachypoda

  • Accepted name: Cycas pachypoda K.D.Hill (2004), accepted by The World List of Cycads (version 2026.08.15) and by GBIF; POWO could not be consulted
  • Former names and synonyms: none
  • Family: Cycadaceae, order Cycadales; section not stated
  • Common names: none attested, in English or in any other language
  • Natural range: southern Vietnam, Bình Thuận and Ninh Thuận provinces
  • IUCN status: Critically Endangered (CR); reassessment by J.D. Bösenberg and T.H. Nguyen published in Red List version 2023-1, after that of H.T. Nguyen (2010, criteria A4acd); CR 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: not documented
  • Habit and adult size: trunk with a large, swollen base; measurements given in the original description, which could not be consulted
  • In the UK, US and Australia: one accession at Montgomery Botanical Center (Florida), received in 2016; no British or Australian record found
  • Toxicity: no data specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas pachypoda

The most visible feature is the base of the trunk, large and strongly swollen: it is this character, which Ken Hill considered distinctive, that gave the species its name (The World List of Cycads). Otherwise the plant shows the characters shared by all Cycas: a crown of pinnate leaves, leaflets with a single midrib, and young leaves that unroll like a crozier. It is dioecious, with male cones and megasporophylls (the fertile leaves of female plants) borne on separate plants.

The full description, with measurements of the leaves, leaflets, cones, megasporophylls and seeds, is in the original description by Hill, Nguyen and Lôc (2004, pp. 176–178, fig. 13), which could not be consulted. Measurements circulating online come without references and are not repeated here.

Hybrids

No hybrid is documented, either in the wild or in cultivation.

Possible confusion

A swollen trunk base is not enough to identify the species. In 2014, when describing Cycas laotica, L.V. Averyanov and colleagues noted that Cycas elephantipes and Cycas siamensis also form trunks with inflated bases, and considered these species, together with Cycas pachypoda, close to their new Laotian cycad.

Cycas elephantipes, from north-eastern Thailand, is the species it most resembles. According to Ken Hill’s description published on The Cycad Pages and reproduced by the llifle encyclopedia, Cycas elephantipes is larger, with bigger leaves and leaflets and, above all, much larger male cones with longer microsporophylls and apical spines. Provenance helps: Cycas pachypoda is known only from southern Vietnam.

Cultivation is misleading too. On the Italian forum Tropicamente, in November 2009, a grower pointed out that a broadened trunk base is found in at least ten South-East Asian species, and in many more when a plant has spent years in a pot with little substrate: a “pachypoda” label on an imported plant should therefore be treated with caution.

Taxonomy

Cycas pachypoda is a name accepted by The World List of Cycads and by GBIF; POWO could not be consulted. The species was described by Ken Hill in the revision of the Vietnamese Cycas he wrote with Nguyễn Tiến Hiệp and Phan Kế Lộc (The Botanical Review 70(2): 134–193, 2004; the species on pp. 176–178). It has no synonym.

Its place within the genus is not stated. Its relationship with Cycas elephantipes is noted on The Cycad Pages; in 2010 a member of the French forum Fous de palmiers wondered whether the two might be a single species, a question that no publication consulted answers.

Etymology and history

The epithet combines the Greek words pachys, “thick”, and podos, “foot”, referring to the large, swollen trunk base (Haynes 2022, cited by The World List of Cycads).

The type was collected by Ken Hill on 20 May 1998 at Vĩnh Hảo, in Tuy Phong district, Bình Thuận province (Hill 5012). The holotype is kept at the Hanoi herbarium (HN), with isotypes in Sydney (NSW), Kew (K), New York (NY), Beijing (PE), Bangkok (BKF), Leiden (L), Paris (P) and St Louis (MO). No history of its introduction into cultivation is documented.

Common names

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

In the wild

Cycas pachypoda is endemic to southern Vietnam: The World List of Cycads records it only from the provinces of Bình Thuận and Ninh Thuận, on the south-east coast of the country, and Species+ confirms Vietnam as its only country.

Its habitat, altitude, substrate and biology (pollination, phenology) are described in the original description, which could not be consulted; no other verifiable source reports them.

Conservation status and regulation

Cycas pachypoda is listed as Critically Endangered (CR). The World List of Cycads cites the assessment by H.T. Nguyen (2010), which used criteria A4acd: criterion A4 denotes a population reduction of at least 80% over a period spanning past and future, estimated from direct observation (a), from a decline in range or habitat quality (c) and from levels of exploitation (d). The reassessment by J.D. Bösenberg and T.H. Nguyen, published in 2023 (Red List version 2023-1), keeps the CR category, according to the Red List data relayed by GBIF (consulted on 24 October 2026); its criteria could not be checked. The specific threats are not described, since the Red List itself could not be consulted directly.

Like every species in the genus except Cycas beddomei, Cycas pachypoda is listed in CITES Appendix II, where the family Cycadaceae has been 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, ask the seller for proof of provenance and prefer plants raised from seed in cultivation. For a Critically Endangered species, every plant taken from the wild weighs on its survival.

Growing Cycas pachypoda

In short: no institution has published growing advice for Cycas pachypoda, and no growing report with a reliable identification is documented on the forums. Without species data, only the general rules for tropical Cycas apply.

Outdoor and in-ground cultivation

No outdoor planting is documented, and the published sources do not describe its habitat. In frost-free tropical or subtropical climates, such as southern Florida, where Montgomery Botanical Center holds the species, an in-ground trial in very free-draining soil would be conceivable, but no result has been published.

Container cultivation

In the United Kingdom and other temperate regions, grow it in a pot, in a heated glasshouse or a bright, frost-free place, in a very free-draining mineral substrate, with watering reduced in the cool season because standing water rots the roots. These are general recommendations for tropical Cycas, not results obtained with this species. The Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published no observation on it.

In cultivation in the UK, US and Australia

In short: very rare in collections; a single garden in these three countries is documented.

  • United States: Montgomery Botanical Center, in Coral Gables (Florida), holds one accession, numbered 20160142, which indicates that it was received in 2016 (online catalogue consulted on 24 October 2026); the garden also declares the species in BGCI PlantSearch. The catalogue does not say whether the plant grows outdoors or under cover.
  • 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).

No first-hand report from a private grower in these countries could be read.

Propagation

Like all Cycas, Cycas pachypoda 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; given the status of the species, look only for seed from cultivated plants and legal sources.

Pests and diseases

No pest or disease specific to the species is documented. Cycad scale insects, including Aulacaspis yasumatsui, can affect any cultivated Cycas.

Cold hardiness

No cold-tolerance data exist for Cycas pachypoda. It is a cycad of tropical southern Vietnam, and nothing allows us to say that it 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 the species. On the French forum Fous de palmiers it appears only in identification threads.

United Kingdom, United States and Australia

No cold reading and no dated growing report are documented, either on forums or from botanic gardens. Treat it as frost-tender; no USDA zone can be given without a documented trial.

Toxicity and precautions

No toxicity analysis specific to Cycas pachypoda has been published. 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 specific to this species is documented.

Frequently asked questions

What does pachypoda mean?

“Thick-footed”, from Greek: the name refers to the large, strongly swollen base of the trunk.

Where does it grow in the wild?

Only in southern Vietnam, in the coastal provinces of Bình Thuận and Ninh Thuận.

Is every cycad with a swollen base a Cycas pachypoda?

No. Several South-East Asian cycads, including Cycas elephantipes and Cycas siamensis, have a trunk swollen at the base, and the character becomes more marked in plants kept for a long time in pots. Without a reliable provenance, identification remains uncertain.

How can it be told from Cycas elephantipes?

According to Ken Hill’s description, Cycas elephantipes is larger, with bigger leaves and leaflets and much larger male cones; it also grows in Thailand, not in Vietnam.

Is it endangered?

Yes, critically. It is listed as Critically Endangered (CR), a category confirmed by the reassessment published in 2023; the 2010 assessment estimated the decline of its population at 80% or more.

Can it be grown outdoors in the UK?

Almost certainly not. No cold data exist and the species comes from tropical southern Vietnam: grow it in a pot under heated glass.

Is it poisonous?

It must be assumed so. No toxicity analysis specific to the species exists, but the Cycas studied contain dangerous toxins, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Hill, K.D., Nguyen, T.H. & Lôc, P.K. (2004). The genus Cycas (Cycadaceae) in Vietnam. The Botanical Review 70(2): 134–193. doi:10.1663/0006-8101(2004)070%5B0134:TGCCIV%5D2.0.CO;2 [Original description (pp. 176–178, fig. 13); subscription article, not consulted: cited after The World List of Cycads. The Vietnam National University repository that lists a copy could not be reached on 13, 18 and 24 October 2026.]
  • Nguyen, H.T. (2010). Cycas pachypoda. The IUCN Red List of Threatened Species 2010: e.T42061A10617113. [CR A4acd assessment; reference taken from The World List of Cycads; page not consulted (access blocked).]
  • Bösenberg, J.D. & Nguyen, T.H. (2023). Cycas pachypoda. The IUCN Red List of Threatened Species: e.T42061A69153836. doi:10.2305/IUCN.UK.2023-1.RLTS.T42061A69153836.en [Reassessment; reference checked on Crossref, CR category relayed by GBIF; Red List page not consulted.]
  • Averyanov, L.V., Nguyen, T.H., Nguyen, S.K., Pham, T.V., Lamxay, V., Bounphanmy, S., Lorphengsy, S., Phan, L.K., Lanorsavanh, S. & Chantthavongsa, K. (2014). Gymnosperms of Laos. Nordic Journal of Botany 32(6): 765–805. doi:10.1111/njb.00498 [Description of Cycas laotica and comparison with the species with swollen trunk bases, including Cycas pachypoda; text consulted.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Source of the etymology taken up 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.]