Cycas changjiangensis

Cycas changjiangensis is a small cycad with a largely underground trunk, endemic to the west of Hainan Island in southern China, where it grows on grassy hills, rocky slopes and in open woodland with a marked dry season. Described in 1998 by the Chinese botanist Nan Liu, this member of the genus Cycas has also been called Cycas hainanensis subsp. changjiangensis. Recent genetic studies merge it into Cycas taiwaniana, but The World List of Cycads still accepts it as a species, and so does this page. The IUCN lists it as Endangered (2022).

Key facts about Cycas changjiangensis

  • Accepted name: Cycas changjiangensis N.Liu (1998), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: Cycas hainanensis subsp. changjiangensis (N.Liu) N.Liu (2004); included in Cycas taiwaniana by Feng and colleagues (2021), a treatment the world checklist does not follow
  • Family: Cycadaceae, order Cycadales
  • Common names: no English name attested; in Chinese 葫芦苏铁 (hu lu su tie)
  • Natural range: China, Hainan Island, Changjiang County (west of the island)
  • IUCN status: Endangered (EN A2acd+4acd; B1ab(iii,v)+2ab(iii,v)), assessment by J. D. Bösenberg published in 2022
  • CITES and other protection: CITES Appendix II; Annex B in the European Union; protected in China as part of Cycas taiwaniana in the 2021 national list of protected wild plants
  • Documented hardiness: no measured value; a British nursery places it in USDA zone 9b, without cultivation data to back it up (see Cold hardiness)
  • Light and soil: in the wild, hills and rocky slopes among grasses and low shrubs, open woodland, or deep sandy soils on flat ground; 600 to 900 m above sea level
  • Habit and adult size: trunk often underground, up to 50 cm by 15 cm, with a base swollen to 25 cm; 25 to 45 leaves, 50 to 130 cm long
  • In the UK, US and Australia: Royal Botanic Garden Sydney (accession of 2021, four plants, and plants raised from seed collected in 1996); photographed at the Darwin botanic garden in 2016; one accession of 2019 at Montgomery Botanical Center (Florida); listed by the Missouri Botanical Garden in BGCI PlantSearch; no record in British gardens (see In cultivation in the UK, US and Australia)
  • Toxicity: no analysis specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas changjiangensis

Look for a dwarf plant whose trunk is almost entirely hidden underground and abruptly swollen at the base, with narrow leaflets twisted on the rachis. In Ken Hill’s key (2008) it is separated from the other Chinese cycad with an underground trunk, Cycas segmentifida, by its leaflets 6 to 10 mm wide and twisted on the rachis. The Flora of China describes it as follows:

  • Trunk: often underground, cylindrical or flask-shaped, sometimes moniliform (constricted at intervals, like a string of beads), up to 50 cm by 15 cm, with a base abruptly swollen to 25 cm across; apex almost hairless; bark grey, almost smooth towards the base.
  • Leaves: 25 to 45, pinnate, 50 to 130 cm by 20 to 40 cm, with a flat, oval-oblong blade.
  • Petiole: almost round in section, 10 to 40 cm, with 9 to 16 spines on each side along its whole length; base densely covered in brown down.
  • Leaflets: 40 to 70 pairs, 0.8 to 1.8 cm apart and set at 55 to 65° to the rachis, straight, leathery, hairless, 10 to 17 cm (up to 23) by 4 to 7 mm (up to 9); midrib raised on both faces, especially above; margins flat or barely recurved; tip tapering and sharp.
  • Cataphylls: triangular-lanceolate, 4 to 7 cm, densely covered in yellow-brown down.
  • Male cones: conical-cylindrical, 15 to 25 cm by 4 to 6 cm; microsporophylls 1.5 to 2 cm, ending in a short, recurved point.
  • Megasporophylls: 40 to 60, crowded, 8 to 13 cm, with silky yellowish-brown down; blade broadly oval or fan-shaped, 5–6 cm by 4–8 cm, comb-like, with 17 to 35 lobes 2 to 3.8 cm long; 1 or 2 hairless ovules on each side.
  • Seeds: 2 to 4 per megasporophyll, green turning yellowish-brown, broadly obovoid or almost spherical, about 2 cm by 1.8 cm; sarcotesta neither spongy nor fibrous.

Hill’s revision (2008) gives much larger measurements for the leaves, megasporophylls and seeds (leaves up to 230 cm, seeds 35 to 40 mm). They are word for word the same as those he gives for Cycas hainanensis, even though he writes that Cycas changjiangensis has smaller seeds; the Flora of China figures, which agree with that difference, are therefore to be preferred.

Hybrids

No named hybrid, natural or garden-made, has been described, but genetics reveals past exchanges with other species. A RADseq study of six cycads from southern China (Tao and colleagues, Frontiers in Genetics, 2021) found little admixture between species, except in the individuals of Cycas dolichophylla, which show substantial genetic admixture with Cycas bifida, Cycas changjiangensis and Cycas balansae. The abstract also reports relatively strong hybridisation signals between Cycas dolichophylla and Cycas szechuanensis and the common ancestor of Cycas taiwaniana and Cycas changjiangensis; the way the sentence is built leaves some doubt about which pairs are meant. This is ancient gene flow in wild populations, not garden hybrids. The study does not, however, allow the low genetic diversity and strong differentiation it describes for the six species as a whole to be attributed to Cycas changjiangensis alone.

Possible confusion

The most likely confusion is with the other members of the “Cycas taiwaniana complex”, a group of very similar cycads from southern China that also includes Cycas hainanensis, Cycas lingshuiensis (published with the spelling “lingshuigensis”), Cycas szechuanensis and Cycas fairylakea (Feng and colleagues, 2021). The last point below comes from the Flora of China:

  • Cycas hainanensis, from the wetter east of Hainan: aerial trunk 0.3 to 1.5 m (exceptionally 3.5 m). According to Hill (2008), Cycas changjiangensis differs in its dwarf, largely underground habit, its smaller megasporophyll blade and its smaller seeds. The World List of Cycads now places Cycas hainanensis in Cycas taiwaniana.
  • Cycas taiwaniana: aerial trunk not swollen at the base, broader leaflets (9 to 16 mm) and a longer petiole (30 to 60 % of the leaf), according to Hill (2008).
  • Cycas segmentifida: also with an underground trunk, but with broader leaflets (9 to 20 mm), lying flat on the rachis (Hill 2008).
  • Cycas siamensis: the Flora of China notes that it resembles Cycas changjiangensis in the grey, abruptly swollen base of the trunk, but that Cycas changjiangensis differs clearly in the midrib strongly raised on the upper face of the leaflets and in its small seeds (about 1.8 cm across), whose sarcotesta is neither spongy nor fibrous.

On young plants without cones these distinctions are hard to apply: a reliable identification needs adult plants and, ideally, reproductive organs.

Taxonomy

Cycas changjiangensis is a name accepted by The World List of Cycads; POWO, behind a protection page, could not be consulted. Nan Liu described it in 1998 in Acta Phytotaxonomica Sinica 36(6): 552–554, from the collection N. Liu 97002, made on 10 June 1997 on grassy hills in Changjiang County, between 800 and 900 m; the holotype is kept at the herbarium of the South China Botanical Garden (IBSC) in Guangzhou. In 2004 the same author reduced it to a subspecies of Cycas hainanensis (Cycas hainanensis subsp. changjiangensis), a combination now treated as a synonym.

Ken Hill, in his revision of the genus in China (2008), kept it at species rank and placed it in section Stangerioides, defined by soft male cones, comb-like megasporophylls, hairless ovules and yellow seeds with a non-fibrous sarcotesta. The debate is not closed. In 2021 Feng and colleagues (Taxon), combining morphology, chloroplast DNA, nuclear genes and microsatellites, recognised only two species in the Cycas taiwaniana complex: Cycas szechuanensis (with Cycas fairylakea) and Cycas taiwaniana, in which they include Cycas changjiangensis, Cycas hainanensis and Cycas lingshuiensis. A 2019 study (Wang and colleagues, Frontiers in Genetics) reached a similar conclusion, the Hainan populations forming a single lineage.

The World List of Cycads has followed this proposal for Cycas hainanensis and Cycas lingshuiensis, but not for Cycas changjiangensis, which remains an accepted species with its own IUCN assessment of 2022. In China, by contrast, the 2021 national list of protected wild plants treats it as part of Cycas taiwaniana (Li and colleagues, 2024). This page follows the world checklist; in recent Chinese sources the plant may appear under the name Cycas taiwaniana.

Etymology and history

The epithet refers to Changjiang County, in the west of Hainan Province, where the species was collected, with the Latin ending -ensis, “from” (Hill 2008; Haynes 2022). The county’s name is written 昌江: it should not be confused with the Yangtze, Chang Jiang (长江), which is transliterated the same way. The plant has nothing to do with the Yangtze basin.

The species was grown outside China even before it was described: Hill (2008) cites plants at the Royal Botanic Gardens Sydney raised from seed collected by Liu in Changjiang County in 1996, and plants grown at Nong Nooch Tropical Garden in Thailand.

Common names

No English common name is attested; the British nursery Trebrown gives “None known”. The Flora of China gives the Chinese name 葫芦苏铁, hu lu su tie: su tie is the Chinese word for cycads, and hu lu means gourd (calabash), probably an allusion to the “flask-shaped” trunk described in the same flora; no published source explains the name outright.

In the wild

Cycas changjiangensis is known only from the west of Hainan Island, in Changjiang County; Hill (2008) cites a specimen from the Bawangling area without stating the extent of the range. The sources describe the habitat in slightly different ways:

  • the Flora of China gives hills and rocky slopes among grasses and low shrubs, or open broadleaved woodland, between 600 and 800 m, under a tropical climate with hot, humid summers and warm, dry winters;
  • the type label mentions grassy hills between 800 and 900 m;
  • Hill (2008) describes seasonally dry woodland on deep sandy soils, on rather flat ground.

All agree on an open habitat; the Flora of China and Hill also point to a marked dry season, very different from the rainforests of the east of the island where Cycas hainanensis grows (Hill 2008). According to the Flora of China, pollination takes place in April and May and the seeds ripen in October and November. No pollinator or seed disperser is documented for the species.

Conservation status and regulation

Cycas changjiangensis is listed as Endangered (EN) by the IUCN, in the assessment by J. D. Bösenberg published in 2022 under criteria A2acd+4acd; B1ab(iii,v)+2ab(iii,v), according to The World List of Cycads; the EN category is confirmed by the IUCN data relayed by GBIF (consulted on 13 October 2026). These criteria reflect a population decline and a restricted range, with a deteriorating habitat and falling numbers. The species was already rated Endangered in Donaldson’s assessment (2003), cited by Hill (2008). Hill noted that fairly large wild populations survived, their habitat not being good farmland, but that others were badly degraded. The Red List page itself could not be consulted directly.

In China, the 2021 national list of protected wild plants treats the species as part of Cycas taiwaniana (Li and colleagues, 2024); the level of protection has not been verified. Like every species in the genus except Cycas beddomei, it is listed in CITES Appendix II, where the family Cycadaceae has been included since 4 February 1977; annotation #4 exempts seeds in particular, whereas live plants need an export permit. The United Kingdom, the United States and Australia 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+ confirms this status (consulted on 12 October 2026). This general information does not replace the official texts: check the rules in force before any purchase or exchange, and prefer plants raised from seed in cultivation.

Growing Cycas changjiangensis

In short: no cultivation guidance specific to the species has been published, but it has long been grown in a few tropical and subtropical collections, notably in Sydney, Darwin and at Nong Nooch in Thailand.

Outdoor and in-ground cultivation

The only clues come from its habitat: open, bright places, well-drained sandy or rocky soils and a long dry season. It therefore needs plenty of light, a mineral soil that does not hold water and little watering while dormant. These are deductions from the wild habitat, not results of published trials. The plants at the Royal Botanic Garden Sydney, in a humid subtropical climate, and those photographed at the George Brown Darwin Botanic Gardens in the tropical north of Australia show that it can be grown outdoors in warm climates; no outdoor trial in Florida, California, the Mediterranean or southern England has been reported.

Container cultivation

Elsewhere it is a pot plant for a frost-free glasshouse. Because the trunk is largely underground and swollen at the base, a deep pot, a very free-draining mineral mix and careful watering, reduced in winter, are the prudent course, again by deduction from the habitat. In France no cultivated plant is documented: on the Fous de palmiers forum the species appears only in the photographs from Darwin, and the Jardin zoologique tropical at La Londe-les-Maures has published nothing on it. On the Italian forum Tropicamente, a grower was looking in vain, in 2023, for an Italian nursery able to supply it.

In cultivation in the UK, US and Australia

In short: present in a few public collections, especially in Australia. A garden listed in the BGCI PlantSearch database (consulted in October 2026) has declared the species at some point, which does not prove that a living plant is there today.

  • Australia: the online catalogue of the Royal Botanic Garden Sydney (updated on 1 October 2026) lists an accession of 2021, S2021-0660, of four plants of garden origin, without a bed number; Hill (2008) already cited plants there raised from seed collected in 1996. In September 2016, a member of the French forum Fous de palmiers photographed plants labelled with this name at the George Brown Darwin Botanic Gardens.
  • United States: the online catalogue of Montgomery Botanical Center (Coral Gables, Florida) lists one accession, whose number points to 2019. The Missouri Botanical Garden (St Louis), whose cycads are grown under glass, lists the species in BGCI PlantSearch.
  • United Kingdom: no British garden lists the species. The Trebrown nursery offers it with a USDA zone rating (see Cold hardiness).

No report from a grower in the United Kingdom, the United States or Australia is documented on the English-language forums that could be read.

Propagation

Like all Cycas, Cycas changjiangensis is dioecious: a male and a female plant are needed to obtain fertile seed. Propagation from seed is shown by the introduction of the species to Sydney from wild-collected seed (Hill 2008), but no germination data specific to the species has been published, nor any propagation by offsets. Microsatellite markers have been developed to study its conservation genetics (Li and colleagues, Conservation Genetics, 2009). Seeds are exempt from CITES under annotation #4; ask for seed from cultivated plants.

Pests and diseases

No pest or disease specific to the species is documented. Like every Cycas, it is exposed to the Asian cycad scale, Aulacaspis yasumatsui, and to rot of the trunk and roots in a substrate that stays too wet, a greater risk for a trunk that is largely underground.

Cold hardiness

There is no measured cold-tolerance data for Cycas changjiangensis. The British nursery Trebrown places it in USDA zone 9b, that is, an average annual minimum of −3.9 to −1.1 °C (25 to 30 °F), but this is a commercial rating with no cultivation observation behind it. No forum post reports a temperature that the species has survived.

The only known cultivations outside China, in Sydney, Darwin and at Nong Nooch, are in subtropical to tropical climates, and no source reports a cold spell. The underground trunk may benefit from the thermal inertia of the soil, but that applies mainly to young plants and does not protect the leaves: it is no proof of hardiness. No result is known from the south of France either, and the Jardin zoologique tropical has no observation to offer. Without data, keep it in a pot, frost-free.

Toxicity and precautions

No toxicity analysis specific to Cycas changjiangensis is documented, but the risk is well documented in the genus: in Cycas, all parts of the plant are poisonous, and the seeds above all. They 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) among plants poisonous to dogs, cats and horses, with vomiting, diarrhoea that may be bloody, jaundice and liver damage that can be fatal. Wear gloves to handle the seeds and their flesh, 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

The published sources describe no traditional use specific to Cycas changjiangensis. Given the toxins of the genus, no part of the plant should be eaten, and its protection rules out any collecting from the wild.

Frequently asked questions

Is the name connected with the Yangtze?

No. The epithet refers to Changjiang County (昌江), in the west of Hainan Island, not to the Chang Jiang river (长江), which is written with different characters.

Is Cycas changjiangensis a synonym of Cycas taiwaniana?

It depends on the authority. Feng and colleagues (2021) and the 2021 Chinese protection list include it in Cycas taiwaniana, but The World List of Cycads, the reference checklist, still accepts it as a species, unlike Cycas hainanensis and Cycas lingshuiensis.

How does it differ from Cycas hainanensis?

By its habit. Cycas changjiangensis is a dwarf with a largely underground trunk swollen at the base, living in the dry west of Hainan; Cycas hainanensis forms an aerial trunk and grows in the rainforests of the east.

Is it endangered?

Yes. The IUCN lists it as Endangered (2022), because of the decline of its habitat and populations. It is covered by CITES Appendix II, by Annex B in the European Union and, in China, by the national list of protected plants.

Can it be grown outdoors in the UK or the cooler parts of the US?

Nobody knows, and there is no evidence for it. There is no measurement of cold tolerance and no outdoor trial outside subtropical and tropical gardens; the prudent course is a pot kept frost-free under glass.

Is it poisonous?

It must be assumed so. There is no analysis 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

  • Liu, N. (1998). A new species of the genus Cycas from Hainan Island, China. Acta Phytotaxonomica Sinica 36(6): 552–554. [Original description; not consulted, reference taken from The World List of Cycads.]
  • Chen, C.J. & Stevenson, D.W. (1999). Cycadaceae. In Wu, Z.Y. & Raven, P.H. (eds), Flora of China, vol. 4: 1–7. Science Press, Beijing; Missouri Botanical Garden Press, St Louis. [Description, Chinese name, habitat; consulted on eFloras.]
  • Hill, K.D. (2008). The genus Cycas (Cycadaceae) in China. Telopea 12(1): 71–118. doi:10.7751/telopea20085804 [Revision for China: key, section, synonymy, habitat, conservation, cultivated plants; full text consulted.]
  • Li, L., Wang, Z.-F., Jian, S.-G., Zhu, P., Zhang, M., Ye, W.-H. & Ren, H. (2009). Isolation and characterization of microsatellite loci in endangered Cycas changjiangensis (Cycadaceae). Conservation Genetics 10: 793–795. doi:10.1007/s10592-008-9664-4 [Genetic markers for conservation; reference checked on Crossref, text not consulted.]
  • Wang, X.-H., Li, J., Zhang, L.-M., He, Z.-W., Mei, Q.-M., Gong, X. & Jian, S.-G. (2019). Population differentiation and demographic history of the Cycas taiwaniana complex (Cycadaceae) endemic to South China as indicated by DNA sequences and microsatellite markers. Frontiers in Genetics 10: 1238. doi:10.3389/fgene.2019.01238 [Two lineages in the complex, Hainan populations grouped together; abstract consulted.]
  • Feng, X.-Y., Wang, X.-H., Chiang, Y.-C., Jian, S.-G. & Gong, X. (2021). Species delimitation with distinct methods based on molecular data to elucidate species boundaries in the Cycas taiwaniana complex (Cycadaceae). Taxon 70: 477–491. doi:10.1002/tax.12457 [Proposed inclusion in Cycas taiwaniana; abstract consulted.]
  • Tao, Y., Chen, B., Kang, M., Liu, Y. & Wang, J. (2021). Genome-wide evidence for complex hybridization and demographic history in a group of Cycas from China. Frontiers in Genetics 12: 717200. doi:10.3389/fgene.2021.717200 [RADseq study of six species from southern China; abstract consulted.]
  • Li, J.H., Zhang, S.W., Yang, X.B. et al. (2024). Composition and floristic characteristics of national key protected wild plants distributed in Hainan Province, China. Guihaia. doi:10.11931/guihaia.gxzw202401028 (ChinaXiv preprint 202405.00161) [Treatment of the species within Cycas taiwaniana in the 2021 national list; abstract consulted.]
  • Bösenberg, J.D. (2022). Cycas changjiangensis. The IUCN Red List of Threatened Species 2022: e.T42045A67339247. [Current assessment, EN; taken from The World List of Cycads, page not consulted.]
  • 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.]