Cycas hoabinhensis

Cycas hoabinhensis is a cycad endemic to northern Vietnam, known only from four provinces south and south-west of Hanoi: Hòa Bình, after which it is named, Hà Nam, Ninh Bình and the former province of Hà Tây. This member of the genus Cycas was described in 2004 by the Vietnamese botanists Phan Kế Lộc and Nguyễn Tiến Hiệp, in the revision of the Cycas of Vietnam that they wrote with the Australian Ken Hill. The IUCN lists it as Endangered. It is one of the least known cycads outside Vietnam, and many figures circulating about it cannot be checked: this page reports only what the sources consulted allow us to confirm.

Key facts about Cycas hoabinhensis

  • Accepted name: Cycas hoabinhensis P.K.Lôc & T.H.Nguyên (2004), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: no synonym; before its publication the name circulated in quotation marks as a provisional name (2003)
  • Family: Cycadaceae, order Cycadales
  • Common names: no English name; the British nursery Trebrown gives “None known”
  • Natural range: northern Vietnam (Hòa Bình, Hà Nam and Ninh Bình provinces and the former Hà Tây province)
  • IUCN status: Endangered (EN), in the reassessment by T. H. Nguyễn published in 2023, after that of 2010 (criteria A2acd+4acd; B1ab(ii,iii,v)+2ab(ii,iii,v)); category confirmed by the Red List data relayed by GBIF
  • CITES and other protection: CITES Appendix II; Annex B in the European Union; present in at least one protected area in Vietnam (2003)
  • Documented hardiness: no data (see Cold hardiness)
  • Light and soil: not documented in the accessible sources (see In the wild)
  • Habit and adult size: original description not consulted; no verified measurement (see How to recognise)
  • In the UK, US and Australia: declared in BGCI by the Royal Botanic Garden Sydney and the San Diego Botanic Garden (California)
  • Toxicity: no data for the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas hoabinhensis

The honest answer is that the accessible sources do not allow it to be described precisely. The original description, published in 2004 in The Botanical Review (pages 153 to 155, figure 5), is available only by subscription and could not be read; no other verifiable source reproduces its measurements of the trunk, leaves, cones or seeds.

To see the plant, the best place is the gallery of The World List of Cycads, which in 2026 brings together 28 observations and 48 photographs taken in Vietnam, mostly in Hòa Bình province, but also in Hà Nam and Hanoi. Like all cycads, it is dioecious: male plants carry a cone of microsporophylls, female plants a crown of megasporophylls, the fertile leaves that bear the ovules.

Hybrids

No hybrid, natural or in cultivation, is documented in the sources consulted.

Possible confusion

Without a verifiable description, morphological comparisons cannot be given. What can be said is which other cycads live in the same region according to The World List of Cycads, and with which an identification based on locality alone would be risky:

  • Cycas dolichophylla, much more widespread in northern Vietnam and southern China, recorded among other places in Hòa Bình and Ninh Bình provinces.
  • Cycas sexseminifera, known among other places from Ninh Bình province.
  • Cycas fugax, from the neighbouring province of Phú Thọ, described in the same 2004 revision.

A reliable identification requires the original description, or the opinion of a botanic garden growing plants of known origin.

Taxonomy

Cycas hoabinhensis is a name accepted by The World List of Cycads; POWO could not be consulted directly. The species was published in 2004 by Phan Kế Lộc and Nguyễn Tiến Hiệp in the revision “The genus Cycas (Cycadaceae) in Vietnam” by Ken Hill, Nguyễn Tiến Hiệp and Phan Kế Lộc (The Botanical Review 70(2): 134–193), hence the author citation “P.K.Lôc & T.H.Nguyên”.

The type is the specimen Phan Kế Lộc P3194a, collected in July 1966 at Chi Nê, in Lạc Thủy district, Hòa Bình province; the holotype is kept at the HNU herbarium in Hanoi, with isotypes at HN (Hanoi) and NSW (Sydney) (The World List of Cycads).

The plant was known to botanists before it was described: the IUCN action plan for cycads published in 2003, in the table of Asian species compiled by Ken Hill, C. J. Chen and Phan Kế Lộc, already lists it, with the name in quotation marks, that is, as a species not yet published.

Its place among the sections of the genus could not be checked, since it depends on the original description. The name has not changed since publication.

Etymology and history

The epithet refers to the occurrence of the species in Hòa Bình province, in northern Vietnam (Haynes 2022, as cited by The World List of Cycads). The type specimen, collected in 1966, shows that Vietnamese botanists had seen the plant nearly forty years before it received a name. In 2006 the South African journal Encephalartos devoted an article to it (“Focus on Cycas hoabinhensis”, by Osborne and colleagues), which could not be consulted. No history of its introduction into cultivation outside Vietnam is documented.

Common names

No English common name is attested: the British nursery Trebrown gives “None known”. No Vietnamese name specific to the species could be confirmed by a reliable source.

In the wild

Cycas hoabinhensis is endemic to northern Vietnam. The World List of Cycads records it in Hòa Bình, Hà Nam and Ninh Bình provinces and in the former province of Hà Tây, now part of Hanoi; the type locality is Chi Nê, in Lạc Thủy district (Hòa Bình province).

The 2003 IUCN action plan gave the following figures: a population of 2,500 to 10,000 plants, in strong decline, an extent of occurrence of about 50 km² and a loss of habitat of 50 to 80% over the previous thirty years. It also indicated that the species occurred in at least one protected area, without naming it.

The substrate, altitude and type of forest where it grows are described in none of the sources that could be read. Its pollinators, phenology and seed dispersal are not documented. GBIF holds no occurrence record under this name (consulted on 21 October 2026).

Conservation status and regulation

Cycas hoabinhensis is listed as Endangered (EN) by the IUCN: this is the current category relayed by GBIF (consulted on 21 October 2026). The assessment by Nguyễn Tiến Hiệp published in 2010 used criteria A2acd+4acd; B1ab(ii,iii,v)+2ab(ii,iii,v), which The World List of Cycads still displays: a past and projected population reduction, linked to habitat decline and exploitation, and a small, fragmented range. A reassessment by T. H. Nguyễn was published in version 2023-1 of the Red List (reference checked on Crossref), and the category remained EN; the Red List itself could not be consulted. As early as 2003, the IUCN action plan listed the species as Endangered (criterion A4c).

Like every species in the genus except Cycas beddomei, Cycas hoabinhensis 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 exempt, 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, confirms this status, with Vietnam as the range state (search of 12 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, for a species threatened by collection, choose only plants raised from seed in cultivation.

Growing Cycas hoabinhensis

In short: no growing advice specific to Cycas hoabinhensis has been published, and no grower’s report outside Vietnam could be found.

Outdoor and in-ground cultivation

The 2003 IUCN action plan reported the species as represented in at least one general collection of a botanic garden or public institution, without naming it. In Vietnam, a French collector photographed a plant grown in the city of Hanoi and reported another, sold under this name as a bonsai, whose identity he doubted (Fous de palmiers forum, 2010). No account of open-ground cultivation outside Vietnam is documented, and nothing is known of its soil or light requirements.

Container cultivation

No container growing report has been found. Until data appear, the prudent course in temperate climates is a pot in a glasshouse, in a free-draining compost as for other cycads, kept frost-free in winter; this is general cycad practice, not advice tested on this species.

In cultivation in the UK, US and Australia

BGCI PlantSearch lists two gardens declaring the species (search of 21 October 2026): the Royal Botanic Garden Sydney and the San Diego Botanic Garden, at Encinitas in California. The species is also recorded in the online catalogue of the Royal Botanic Garden Sydney (checked on 19 October 2026). A BGCI entry shows that a garden has declared the species, not that the plant is alive today, and neither source says whether the plants grow outdoors or under glass. No accession was found in the online catalogue of Montgomery Botanical Center (Florida), and no British garden declares it. No report from an English-speaking grower could be read.

Propagation

The plant is dioecious: a male and a female plant are needed to obtain fertile seed. No germination data specific to the species have been published. Seeds are exempt from CITES under annotation #4; for an endangered species, raising plants from legally obtained seed of cultivated origin is the only responsible way to acquire it.

Pests and diseases

No pest or disease specific to the species is documented. Like all cycads, it can be attacked by the Asian cycad scale, Aulacaspis yasumatsui, and a compost that stays wet for long periods encourages root rot.

Cold hardiness

There are no cold-tolerance data for Cycas hoabinhensis: no source says what temperature it can withstand, in the wild or in cultivation. The British nursery Trebrown rates it USDA zone 9b, that is, an average annual minimum of −3.9 to −1.1 °C (25 to 30 °F); this is a commercial rating, without growing observations to support it.

Mediterranean experience

No growing result has been published in Europe, in the open ground or in a pot, and no dated frost event concerns the species. French and Italian forums report no experience, and the Jardin zoologique tropical has published no observation.

United Kingdom, United States and Australia

No cold reading or dated growing report was found, either on forums or from botanic gardens; the plants declared at Sydney and Encinitas, both in mild coastal climates, have produced no published observation. In the UK, treat it as a plant for a frost-free glasshouse.

Toxicity and precautions

No toxicity analysis specific to Cycas hoabinhensis has been found, 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, with vomiting, diarrhoea and liver damage that can be fatal. 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 traditional use specific to Cycas hoabinhensis is documented in the sources consulted. The only uses reported are ornamental, in gardens in Vietnam.

Frequently asked questions

Where does the name hoabinhensis come from?

From Hòa Bình province, in northern Vietnam. It was there, at Chi Nê in Lạc Thủy district, that the specimen on which the description is based was collected in 1966.

Where does it grow?

Only in northern Vietnam, in Hòa Bình, Hà Nam and Ninh Bình provinces and the former province of Hà Tây, now part of Hanoi.

Is it endangered?

Yes. The IUCN lists it as Endangered (2010 assessment, category kept by the reassessment published in 2023); habitat decline and the exploitation of the plants are among the criteria used.

Is it protected?

Partly. It occurs in at least one protected area in Vietnam, and it is covered by CITES Appendix II, like the whole family, and by Annex B in the European Union.

What does it look like?

The accessible sources do not describe it in a verifiable way. The 2004 original description could not be consulted; to get an idea, look at the photographs published by The World List of Cycads.

Can it be grown outdoors in the UK or the US?

Nobody knows. There are no cold data and no growing reports; the only rating, USDA zone 9b, is a nursery’s commercial classification. In the UK, keep it under glass.

Is it poisonous?

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

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Hill, K.D., Nguyễn, 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[0134:TGCCIV]2.0.CO;2 [Original description of Cycas hoabinhensis (pp. 153–155, fig. 5); full text not consulted (paywall), reference checked on Crossref and The World List of Cycads.]
  • Hill, K.D., Chen, C.J. & Lôc, P.K. (2003). Regional overview: Asia. In: Donaldson, J.S. (ed.), Cycads. Status Survey and Conservation Action Plan, chapter 5. IUCN/SSC Cycad Specialist Group, Gland and Cambridge. [Table 5.1: species not yet published, EN A4c, in a protected area, population, extent of occurrence and habitat loss; table 8.1: presence in a general collection; full text consulted.]
  • Osborne, R., Hill, K.D., Nguyễn, T.H. & Lôc, P.K. (2006). Focus on Cycas hoabinhensis. Encephalartos 87: 9–13. [Reference taken from The World List of Cycads; not consulted.]
  • Nguyễn, T.H. (2023). Cycas hoabinhensis. The IUCN Red List of Threatened Species 2023-1: e.T42047A68902426. doi:10.2305/IUCN.UK.2023-1.RLTS.T42047A68902426.en [Current assessment (EN); reference checked on Crossref, category relayed by GBIF; text not consulted.]
  • Nguyễn, H.T. (2010). Cycas hoabinhensis. The IUCN Red List of Threatened Species 2010-3: e.T42047A10637474. doi:10.2305/IUCN.UK.2010-3.RLTS.T42047A10637474.en [Previous assessment, criteria as given by The World List of Cycads; 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, as cited 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.]