Cycas chenii

Cycas chenii is a cycad without an above-ground trunk, endemic to the upper course of the Red River (Yuanjiang) in south-central Yunnan, China, where it grows in the shade of subtropical evergreen broadleaved forest on steep slopes. Described only in 2015 by botanists of the Kunming Institute of Botany, this species of the genus Cycas is named after the Chinese botanist Chia-Jui Chen and is separated from its sister species, Cycas guizhouensis, by its underground stem. Fewer than 500 plants are known, and the IUCN lists it as Endangered.

Key facts about Cycas chenii

  • Accepted name: Cycas chenii X.Gong & Wei Zhou (2015), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: none
  • Family: Cycadaceae, order Cycadales
  • Common names: none in English; in Chinese 陈氏苏铁 (chen shi su tie, “Chen’s cycad”)
  • Natural range: China, Yunnan, upper Red River basin (Chuxiong and Honghe prefectures)
  • IUCN status: Endangered (EN, criterion B1ab(iii,v)), assessment by W. Zhou and X. Gong published in Red List version 2023-1, EN according to GBIF
  • CITES and other protection: CITES Appendix II (listing of the whole family); Annex B in the European Union; in China, a wild plant under first-class state protection, like all Chinese Cycas
  • Documented hardiness: no data (see Cold hardiness)
  • Light and soil: in the wild, understorey of subtropical evergreen forest on steep slopes, on substrates ranging from limestone to shale; 500 to 1,300 m (up to about 1,600 m according to later sampling)
  • Habit and adult size: underground stem (acaulescent); the leaf and cone measurements of the original description could not be checked
  • In the UK, US and Australia: no record in any botanic garden; in China, grown in the conservation collection of Kunming Botanical Garden
  • Toxicity: no analysis specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas chenii

The decisive feature is the stem: Cycas chenii is acaulescent, its stem stays underground and only the leaves emerge from the soil. According to the authors of the description (Zhou, Guan and Gong 2015), this is what separates it at once from its closest relative, Cycas guizhouensis. Like all species of section Stangerioides, it has soft male cones, megasporophylls with a comb-like blade, hairless ovules and yellow seeds whose fleshy coat lacks a fibrous layer (Hill 2008, for the definition of the section).

The original description, published in the Journal of Systematics and Evolution, includes a full illustrated description and a morphological and chromosomal comparison with related species, but its full text (paywalled) could not be consulted. Leaf, leaflet, cone, megasporophyll and seed measurements and a chromosome formula that circulate online could not be traced to a readable source and are not given here. To identify a plant, refer to the original paper.

Hybrids

No natural or garden hybrid is documented. Genetic studies show, on the contrary, a clear separation from the sister species: according to Wang and colleagues (American Journal of Botany, 2026), Cycas chenii and Cycas guizhouensis are genetically distinct lineages that split in the early Miocene, and their divergence seems to stem mainly from geographical isolation in different river basins, perhaps after shifts in river courses, rather than from ecological differences: their environmental niches proved statistically indistinguishable.

Possible confusion

The most likely confusion is with Cycas guizhouensis, the sister species, which grows in the valleys of the Nanpan and Qingshui rivers, between south-western Guizhou, eastern Yunnan and north-western Guangxi, on limestone slopes covered in low scrub (Hill 2008). According to Zhou and colleagues (2015), Cycas chenii is told at once by its underground stem. Hill (2008), however, describes the stem of Cycas guizhouensis as “arborescent to acaulescent”, up to 1 m tall: on young plants this feature should be used with caution, taking the origin into account.

Other cycads of section Stangerioides grow in the same region, among them Cycas simplicipinna and Cycas tanqingii, with which the original description compares it. The detailed differences it gives (chromosomes, blackening of dried leaves, shape of the megasporophyll blade) could not be checked and are not repeated here.

Taxonomy

Cycas chenii is accepted by The World List of Cycads; POWO could not be consulted directly. Wei Zhou, Meng-Meng Guan and Xun Gong, of the Kunming Institute of Botany (Chinese Academy of Sciences), described it in 2015 in “Cycas chenii (Cycadaceae), a new species from China, and its phylogenetic position”, Journal of Systematics and Evolution 53(6): 489–498; the name is attributed to X. Gong and Wei Zhou. The type is the collection W. Zhou 201235, made in 2012 at Dutian, in Shuangbai county (Yunnan), at 1,100 m; the holotype is in the herbarium of the Kunming Institute of Botany (KUN).

To place the species, the authors compared 16 species of Cycas using DNA sequences from two plastid regions, the nuclear ribosomal spacers (ITS) and two nuclear regions: Cycas chenii forms a distinct group, related to Cycas guizhouensis, within section Stangerioides. The name has not changed since its publication.

Etymology and history

The epithet chenii honours Professor Chia-Jui Chen (Chen Jiarui), a botanist of the Institute of Botany of the Chinese Academy of Sciences, for his work on the Cycas of China (Haynes 2022, taken up by The World List of Cycads). With D. W. Stevenson he wrote the account of the Cycadaceae in the Flora of China (1999), and he had described Cycas hainanensis in 1975 (Hill 2008).

The species was described late, in 2015, from plants collected in 2012. That same year, the Kunming team sampled all the populations then known for a genetic study published in 2017; a second study, published in 2024, examined ten.

Common names

No English common name is attested. In Chinese the species is called 陈氏苏铁, chen shi su tie, literally “Chen’s cycad”, the name used in the review of the Cycas of China published in 2022 in Biodiversity Science.

In the wild

Cycas chenii lives only in Yunnan, along the upper course of the Red River, called the Yuanjiang in China, in Chuxiong and Honghe prefectures. According to the original description, as quoted by Yang and colleagues (2017), it grows on steep slopes between 500 and 1,300 m, on substrates ranging from limestone to shale, under subtropical evergreen broadleaved forest; these warm, dry valleys of south-western China may have served as refuges during the climatic swings of the Quaternary. The localities of the description, according to the English-language Wikipedia (the only source read for this list), are Dutian and Qingshuihe (Shuangbai county) and Menglong and Lianhua (Honghe county); the 2022 review lists the counties of Eshan, Honghe, Shiping, Shuangbai, Xinping and Yuanjiang. The populations sampled in 2012 lay between about 490 and 1,600 m.

The river has shaped the species’ history. In 2017 six populations were known, four on the north-east bank of the Red River and two on the south-west bank: chloroplast DNA splits them into two groups that match the two banks, so the river seems to act as a barrier to gene flow. The 2024 study (Wu and colleagues, Conservation Genetics), covering ten populations, found three genetic groups aligned with their respective watercourses and three demographic “bottlenecks” over the last five million years; the species’ genetic diversity proved higher than that of other Cycas.

Conservation status and regulation

Cycas chenii is listed as Endangered (EN, criterion B1ab(iii,v)) by the IUCN: the assessment, by W. Zhou and X. Gong, was published in Red List version 2023-1 (reference checked on Crossref), and the EN category is confirmed by the IUCN data relayed by GBIF (consulted on 21 October 2026). The criterion reflects a very small range, with a decline in habitat quality and in the number of mature plants. The Red List itself could not be consulted directly.

The authors of the species estimated the total population at fewer than 500 plants, all known populations lying far from any protected area; each population sampled in 2012 held fewer than 100 plants. The threats cited are clearing for farming and over-collection (Yang and colleagues 2017). The 2017 study calls the species “critically endangered” (the authors’ wording, not a Red List category) and proposes at least two protected areas, one on each bank, and seed collection from every population for conservation outside the wild; the 2024 study proposes separate strategies for each of the three genetic groups.

In China, every species of Cycas is on the national list of wild plants under first-class protection (Xi and colleagues 2022). Like every species in the genus except Cycas beddomei, Cycas chenii is covered by CITES Appendix II through the listing of the whole family Cycadaceae; annotation #4 exempts seeds in particular, whereas live plants require 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, in the version set by Commission Regulation (EU) 2026/1383, applicable since 29 June 2026. Species+, the CITES database, has no entry of its own for this recently described species: its status derives from the family listing. This information does not replace the official texts: check the rules in force before any purchase or exchange.

Growing Cycas chenii

In short: outside China, Cycas chenii is not grown in any documented collection, and no growing advice has been published. In China it is part of the conservation collection of Kunming Botanical Garden, where its coralloid roots were studied in 2023 alongside those of nine other Cycas (Wang and colleagues, Microorganisms), and Xishuangbanna Tropical Botanical Garden declares one accession in BGCI PlantSearch.

Outdoor and in-ground cultivation

Its natural setting gives a few clues: an understorey plant, to be kept in filtered light rather than full sun, in a well-drained soil, with an underground stem to be protected from standing water. These are deductions from its habitat, not growing results, and no outdoor trial has been reported outside China.

Container cultivation

No account of pot culture has been found. In the absence of data, it is best treated as a plant for a pot in a frost-free glasshouse, in a free-draining mineral substrate. The Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published no observation on this species.

In cultivation in the UK, US and Australia

No record. The species does not appear in BGCI PlantSearch for any garden in these three countries (consulted in October 2026), nor in the online catalogues of Montgomery Botanical Center, Fairchild Tropical Botanic Garden, the Royal Botanic Garden Sydney or the Royal Botanic Gardens Victoria. No report from a private grower could be read; PalmTalk and Dave’s Garden could not be consulted. Given its rarity and its protection in China, only seed of legal, documented origin should be considered.

Propagation

Like all Cycas, Cycas chenii 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. Yang and colleagues (2017) recommend collecting representative seed from every surviving population, especially the most genetically diverse, for conservation collections.

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 stem and root rot in an overly wet substrate, a risk that is greater for an underground stem.

Cold hardiness

There are no cold-tolerance data for Cycas chenii: no measurement, no nursery rating and no outdoor growing report. The species, recently described, is almost absent from collections, and no USDA zone can be attributed to it from any source.

European experience

No growing result has been published in Europe, and no dated frost episode concerns the species. The French forum Fous de palmiers and the Italian forum Tropicamente have no message on it. 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 clue is its habitat: warm, dry valleys of Yunnan between 500 and 1,300 m (up to about 1,600 m), whose minimum temperatures are not given by any source consulted. The underground stem may protect the plant through the thermal inertia of the soil, especially when young, but it does not protect the leaves and is no proof of hardiness. No USDA zone can be given.

Toxicity and precautions

No toxicity analysis specific to Cycas chenii 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. 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. Wear gloves to handle the seeds and their pulp, 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

The sources consulted describe no traditional use specific to Cycas chenii. The over-collection cited among its threats (Yang and colleagues 2017) is not detailed; given the toxins of the genus, no part of the plant should be eaten.

Frequently asked questions

How can it be told from Cycas guizhouensis?

Mainly by its stem, which stays underground in Cycas chenii, and by its origin: Cycas chenii grows along the Red River in south-central Yunnan, Cycas guizhouensis in the Nanpan and Qingshui valleys. Genetically they are two distinct lineages, separated for millions of years.

Where does it grow in the wild?

Only in Yunnan, along the upper Red River, in Chuxiong and Honghe prefectures, in the shade of subtropical forest on steep slopes, between about 500 and 1,300 m.

Who is it named after?

The Chinese botanist Chia-Jui Chen, for his work on the Cycas of China.

Is it endangered?

Yes. Fewer than 500 plants are known, in small populations outside protected areas, threatened by clearing and over-collection. The IUCN lists it as Endangered; in China it has first-class protection.

Is it available in the trade?

Not to our knowledge. No nursery or forum consulted offers it, and the only documented collections are in Chinese botanic gardens.

Can it be grown outdoors in the UK?

Nobody knows. No cold data exist; in the absence of evidence, keep it in a pot under frost-free glass.

Is it poisonous?

It must be assumed so. No analysis exists for the species, but all the Cycas studied contain toxins dangerous to people and animals, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Zhou, W., Guan, M.-M. & Gong, X. (2015). Cycas chenii (Cycadaceae), a new species from China, and its phylogenetic position. Journal of Systematics and Evolution 53(6): 489–498. doi:10.1111/jse.12153 [Original description, morphological and chromosomal comparisons, phylogenetic position; abstract only consulted (paywalled).]
  • Hill, K.D. (2008). The genus Cycas (Cycadaceae) in China. Telopea 12(1): 71–118. doi:10.7751/telopea20085804 [Definition of section Stangerioides and description of Cycas guizhouensis; full text consulted.]
  • Yang, R., Feng, X.-Y. & Gong, X. (2017). Genetic structure and demographic history of Cycas chenii (Cycadaceae), an endangered species with extremely small populations. Plant Diversity 39(1): 44–51. doi:10.1016/j.pld.2016.11.003 [Populations, habitat, threats, genetic structure; full text consulted.]
  • Wu, L.-X., Wang, Y.-Q., Xiao, S.-Y., Wang, Y.-H., Liu, J., Gong, X. & Feng, X.-Y. (2024). Rivers have shaped the phylogeography of a narrowly distributed cycad lineage in Southwest China. Conservation Genetics 25(2): 439–453. doi:10.1007/s10592-023-01579-2 [Ten populations, three genetic groups; abstract consulted.]
  • Wang, Y.-Q., Liu, J., Xiao, S.-Y., Xi, H.-H., Gong, X. & Feng, X.-Y. (2026). Geographic isolation promoted species divergence of two closely related Cycas species in distinct river basins. American Journal of Botany. doi:10.1002/ajb2.70270 [Divergence from Cycas guizhouensis; abstract consulted.]
  • Xi, H.-H., Wang, Y.-Q., Pan, Y.-Z., Xu, T., Zhan, Q.-Q., Liu, J., Feng, X.-Y. & Gong, X. (2022). Resources and protection of Cycas plants in China. Biodiversity Science 30(7): 21495. doi:10.17520/biods.2021495 [Review in Chinese with English abstract; tables consulted.]
  • Wang, Z., Liu, J., Xu, H., Liu, J., Zhao, Z. & Gong, X. (2023). Core microbiome and microbial community structure in coralloid roots of Cycas in ex situ collection of Kunming Botanical Garden in China. Microorganisms 11(9): 2144. doi:10.3390/microorganisms11092144 [Species present in the Kunming collection; full text consulted.]
  • Zhou, W. & Gong, X. (2023). Cycas chenii. The IUCN Red List of Threatened Species 2023: e.T103632155A103632285. doi:10.2305/IUCN.UK.2023-1.RLTS.T103632155A103632285.en [Current assessment, EN B1ab(iii,v); reference checked on Crossref, category relayed by GBIF and The World List of Cycads, text 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; taken up 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.]