Cycas debaoensis: the fern-leaved Debao cycad of Guangxi

Cycas debaoensis is a small, almost trunkless cycad from the limestone hills of western Guangxi, in southern China, where only a few populations are known. Discovered in 1996 and described in 1997, this member of the genus Cycas is famous for its leaves, which are divided two or three times, giving the plant the airy look of a fern rather than of a typical cycad. It is listed as Critically Endangered by the IUCN and is a first-class protected plant in China, yet it has become a sought-after collector’s plant, now held by botanic gardens in several countries.

Key facts about Cycas debaoensis

Accepted name: Cycas debaoensis Y.C.Zhong & C.J.Chen (1997), accepted by The World List of Cycads (version 2026.08.15); the World Checklist of Vascular Plants (WCVP), on which POWO is based, also accepts it (consulted through GBIF on 31 October 2026)
Former names and synonyms: Cycas panshuiensis Y.Yang (2017)
Family: Cycadaceae, order Cycadales; section Stangerioides
Common names: Debao cycad; multipinnate cycad (a trade name also suited to Cycas multipinnata); in Chinese 德保苏铁 (de bao su tie) (see Common names)
Natural range: China, western Guangxi (Debao and Napo counties); a 2022 article also cites Yunnan, which the world checklist does not list
IUCN status: Critically Endangered (CR A4cd), category confirmed by the reassessment by J. D. Bösenberg published in 2023, which replaced that of W. Tang (2010)
CITES and other protection: CITES Appendix II; Annex B in the European Union; first-class protected plant in China
Documented hardiness: a garden plant in Walnut Creek (California) unharmed by short dips to about −4 °C (the mid-20s °F); a US extension service gives USDA zone 9b and a reported, unconfirmed hardiness of −8.3 °C (17 °F) (see Cold hardiness)
Light and soil: in the wild, limestone slopes, in thickets, open woodland or mixed forest; in cultivation, sun with some afternoon shade and very sharp drainage
Habit and adult size: trunk almost underground, rising at most 40 to 70 cm above the soil; 3 to 15 leaves, 1.3 to 3 m long
In the UK, US and Australia: Montgomery Botanical Center (eight accessions from 2003 to 2020), Fairchild (2021), the Ruth Bancroft Garden; Royal Botanic Garden Sydney (2009 and 2021); listed by Kew, Edinburgh and Wisley in BGCI PlantSearch (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 debaoensis

Its divided leaves identify it at a glance: in almost all Cycas the leaflets are simple, whereas here each primary leaflet is itself divided into secondary leaflets, then forked into narrow segments. Only Cycas multipinnata shares this structure (Hill 2008). The two main descriptions, Ken Hill’s revision (2008) and the Flora of China, differ on several measurements; both are given below.

Trunk: almost underground, 15 to 20 cm in diameter at the narrowest point (Hill); rising up to 40 cm, rarely 70 cm, above the soil and 25 to 40 cm across, sometimes clumping, with grey-brown bark, scaly towards the top (Flora of China).
Leaves: 3 to 15 in the crown; 250 to 300 cm long according to Hill, 1.3 to 2.7 m according to the Flora of China, which describes them as three times pinnate, deep green and semi-glossy, with white down shed as the leaf expands.
Petiole: 80 to 150 cm, 30 to 50 % of the leaf, spiny along its whole length (Hill); 0.6 to 1.3 m with 20 to 55 short spines on each side (Flora of China).
Leaflets: 6 to 14 pairs of primary leaflets, the middle ones 40 to 70 cm long, each carrying 3 to 5 pairs of secondary leaflets forked two or three times; the final segments are linear, 10 to 22 cm (up to 28) by 0.8 to 1.5 cm, shiny green above, paler beneath, with a long, tapering tip (Flora of China). Hill gives median leaflets 500 to 560 mm long, pinnately divided then forked towards the tip, broadest below the middle.
Cataphylls: narrowly triangular, soft, hairy, 70 to 90 mm long (Hill).
Male cones: spindle-shaped, cream, 20 to 30 cm by 5 to 7 cm, soft, the microsporophylls without an apical spine (Hill); 13 to 25 cm by 4 to 9 cm according to the Flora of China.
Megasporophylls: 12 to 14 cm (Hill) or 15 to 20 cm (Flora of China), with brown or yellow-brown down, bearing 2 to 6 hairless ovules; blade round to fan-shaped, 6 to 9 cm across, deeply divided into 26 to 28 (Hill) or 39 to 51 (Flora of China) soft, thread-like lobes 3 to 6 cm long.
Seeds: ovoid, 25 to 27 mm by 20 to 22 mm, with a yellow sarcotesta 2 mm thick, no fibrous layer and a warty sclerotesta (Hill); 3 to 3.5 cm by 2.5 to 3 cm, green turning yellowish-brown, according to the Flora of China.

Hybrids

No natural hybrid is documented. In cultivation, hybrids are offered or grown under the names Cycas revoluta × Cycas debaoensis and Cycas panzhihuaensis × Cycas debaoensis: the American nursery Jungle Music has listed the latter, and a grower in Ravenna (Emilia-Romagna, Italy) reports on the Tropicamente forum that a Cycas revoluta × Cycas debaoensis doubled in size in the summer of 2010. The parentage of these plants rests on the sellers’ word, and their hardiness has not been measured.

Possible confusion

The only species it can really be confused with is Cycas multipinnata, the other Cycas with divided leaves, from eastern Yunnan, northern Vietnam and western Guangxi. According to Hill (2008), Cycas debaoensis differs in its shorter and more numerous leaves (3 to 15, against 1 or 2 leaves up to 6 m long), its narrower, thicker leaflets, broadest below the middle, and its usually longer megasporophylls with a larger blade. The Flora of China adds its long-tapering segments, its broader megasporophyll blade divided into 39 to 51 thread-like lobes, and its drier, sunnier habitat. Cycas bifida, whose leaflets are only forked, not pinnately divided, completes the group in Hill’s key.

In cultivation the two species are mixed up: the Ruth Bancroft Garden in California writes that it is not entirely sure its plant, received as a donation, is the true Cycas debaoensis, because of this confusion. On young plants the distinguishing characters are hard to see; seed of documented origin is the safest choice.

Taxonomy

Cycas debaoensis is a name accepted by The World List of Cycads; the World Checklist of Vascular Plants (WCVP), on which POWO is based, also accepts it (consulted through GBIF on 31 October 2026). Y. C. Zhong and C. J. Chen described it in 1997 in Acta Phytotaxonomica Sinica 35(6): 571, from the collection Y. C. Zhong 8762, made on 27 August 1997 in the rocky mountains of Debao County, at 850 m, on brown calcareous soil near large rocks. The only synonym listed by the world checklist is Cycas panshuiensis Y.Yang, published in 2017.

The type proved complicated. In 2022 Yong Yang and David Ferguson (PhytoKeys 211) found nine sheets of Zhong 8762 at the herbarium of the Institute of Botany in Beijing (PE), seven labelled as holotype and two as isotype, and one sheet that also holds seeds collected in October 1998, a separate gathering. They therefore designated a lectotype, the sheet PE00047578, which bears the authors’ handwriting and both leaves and megasporophylls with young seeds; the other sheets, at PE and GXMI, are isolectotypes.

Hill (2008) places the species in section Stangerioides, with soft male cones, a loose sarcotesta without a fibrous layer and a warty sclerotesta, characters shared with Cycas multipinnata and a wider group of species. The original description is the 1997 paper by Zhong and Chen.

Etymology and history

The epithet refers to Debao County, in western Guangxi, with the Latin ending -ensis, “from” (Hill 2008; Haynes 2022). According to Hill (2008), this remarkable species was only discovered in 1996 and described the following year. Its rapid entry into cultivation shows in the botanic garden records: the first accessions of Montgomery Botanical Center, in Florida, date from 2003 judging by their numbers, and in 2006 the newsletter of The Cycad Society already carried articles on growing it in central Florida and in Hawaii (not consulted).

Common names

Two English names are in use. Debao cycad is the common name shown in the online catalogue of the Royal Botanic Garden Sydney. Multipinnate cycad is used by the British nursery Trebrown and by the Mississippi State University extension service; it is a descriptive trade name that could equally apply to Cycas multipinnata. The Flora of China gives the Chinese name 德保苏铁, de bao su tie, “Debao cycad”.

In the wild

Cycas debaoensis is known from a very small area of western Guangxi. Hill (2008) cites two populations, in Debao and Napo counties, in mixed evergreen and deciduous woodland on limestone slopes, and notes that most of the forest habitat has been cleared or severely degraded. The Flora of China describes thickets and open woods of small trees on dry, sunny, open slopes of limestone hills between 700 and 1,000 m, and placed the known population in a very small area, about 20 hectares, in a village. The Ruth Bancroft Garden, by contrast, describes limestone cliffs and ledges at about 3,000 ft (about 900 m) often bathed in mist during the warm season; it gives no source for this. Yang and Ferguson (2022), citing a 2022 study, mention populations in Yunnan as well as Guangxi; The World List of Cycads lists only Guangxi.

According to the Flora of China, pollination takes place in March and April and the seeds ripen in November. No pollinator or seed disperser is documented for the species.

Conservation status and regulation

Cycas debaoensis is listed as Critically Endangered (CR) by the IUCN. The World List of Cycads gives criterion A4cd, from the assessment by W. Tang (Red List 2010); the reassessment by J. D. Bösenberg, published in Red List version 2023-1, replaced it, and the CR category is confirmed by the IUCN data relayed by GBIF (consulted on 21 October 2026). Criterion A4 refers to a population reduction over a period covering both past and future, here attributed to exploitation and habitat loss. Donaldson’s assessment (2003), cited by Hill, already rated it CR.

The threats are well identified: Hill (2008) describes the species as already severely depleted and at risk from horticultural collectors, and the Flora of China warned in 1999 that, without conservation measures, it would disappear from the wild within ten years. In China it is listed as a first-class species in the national list of key protected wild plants (Yang and Ferguson 2022).

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 and gives China as the only range state (consulted on 21 October 2026). This general information does not replace the official texts: check the rules in force before any purchase or exchange, and buy only plants raised from seed in cultivation.

Growing Cycas debaoensis

In short: it is grown outdoors in California and Florida and under glass elsewhere; it needs very sharp drainage, generous feeding and some shade in the afternoon, and rot is the failure most often reported.

Outdoor and in-ground cultivation

The most detailed first-hand account comes from the Ruth Bancroft Garden, in Walnut Creek (California), whose plant produced its first male cone in 2023. The garden finds that it tolerates full sun and fairly scant watering, but looks lusher and more robust with some afternoon shade and more generous irrigation; like almost all cycads it needs very sharp drainage there, and it responds well to generous doses of nitrogen. The garden also passes on anecdotal reports from Florida that growth is fastest in a mist house. Montgomery Botanical Center, whose collection is grown outdoors at Coral Gables in southern Florida, holds eight accessions (see below).

In a Mediterranean climate, the experience reported from Italy is less encouraging, though it concerns plants in pots. A grower in Ravenna (Emilia-Romagna) reports on the Tropicamente forum that the leaves of their Cycas debaoensis deteriorate quickly even in an acid soil (2014), while a grower in Ragusa, in Sicily, reports in 2018 a third attempt, the previous plants having rotted for no obvious reason, in a mix of grit and coarse sand watered sparingly. No in-ground result is known from France, and the Jardin zoologique tropical at La Londe-les-Maures has published no observation on the species.

Container cultivation

In the United Kingdom, northern Europe and the colder parts of the United States, it is a plant for a deep pot, kept in a bright glasshouse or conservatory in winter. The Ravenna grower kept young plants indoors in winter and still grew the species in a deep pot in 2018. Given the rot reported in Italy, a very free-draining mineral mix, warmth and restrained watering in cool weather are the prudent course; these are deductions from the reports above, not a tested protocol. The Italian growers quoted above used neutral to acid mixes.

In cultivation in the UK, US and Australia

In short: well represented in American collections, present in Sydney, and listed by three British gardens. 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.

United States: the online catalogue of Montgomery Botanical Center (Coral Gables, Florida) lists eight accessions, four from 2003 and the others from 2008, 2019 and 2020 judging by their numbers; that of Fairchild Tropical Botanic Garden lists an accession of 2021. The Ruth Bancroft Garden (Walnut Creek, California) grows it outdoors (see Growing). BGCI PlantSearch adds some twenty other gardens, among them The Huntington, Ganna Walska Lotusland, San Diego Botanic Garden and the San Diego Zoo in California, Longwood Gardens, The New York Botanical Garden, the United States Botanic Garden and the National Tropical Botanical Garden in Hawaii.
Australia: the online catalogue of the Royal Botanic Garden Sydney (updated on 1 October 2026) lists a plant in bed 51l (accession of 2009) and two in bed 51s (accession of 2021), all of garden origin, under the name “Debao Cycad”. Cairns Botanic Gardens, James Cook University in Townsville and the System Garden of the University of Melbourne list it in BGCI PlantSearch.
United Kingdom: the Royal Botanic Gardens, Kew, the Royal Botanic Garden Edinburgh and RHS Garden Wisley list the species in BGCI PlantSearch; Kew and Edinburgh grow their cycads under glass, and no growing result has been published.

No dated report from a private grower in the United Kingdom, the United States or Australia has been published.

Propagation

Like all Cycas, Cycas debaoensis is dioecious: a male and a female plant are needed to obtain fertile seed. Propagation is from seed. A grower on the Tropicamente forum notes that seedlings show divided leaves from the first leaf onwards (2010), which helps to check young plants. No germination data specific to the species has been published, and no source confirms propagation by offsets. Seeds are exempt from CITES under annotation #4; buy only seed or plants from cultivated sources.

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. The main problem reported in cultivation is rot of the underground trunk and roots, mentioned by Italian growers (Tropicamente, 2018).

Cold hardiness

Measured data are few. The Ruth Bancroft Garden reports that its plant, outdoors in Walnut Creek, was unharmed by short dips into the mid-twenties Fahrenheit, that is, to about −4 °C, adding that its ultimate frost tolerance is unknown. The Mississippi State University extension service rates the species for USDA zone 9b and says it is “reportedly hardy” to 17 °F (−8.3 °C), while noting that some sources give only zone 10a; the British nursery Trebrown also places it in zone 9b, a commercial rating. These ratings are not backed by published trials.

No dated cold result is known from Europe: the Italian growers quoted above kept their plants in pots, protected in winter, and there is no in-ground record from the south of France. In the wild, the Flora of China describes dry, sunny limestone slopes at 700 to 1,000 m, but gives no minimum temperature. In the UK, overwinter it frost-free under glass; in California and Florida, the Ruth Bancroft experience suggests that brief light frosts are tolerated by established plants.

Toxicity and precautions

No toxicity analysis specific to Cycas debaoensis is documented, 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) among plants poisonous to dogs, cats and horses. Treat the plant as poisonous: keep seeds and leaves out of reach of children and pets, wear gloves to clean the seeds and, 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 of Cycas debaoensis. Its only documented use is ornamental, and it is precisely collecting for horticulture that Hill (2008) identifies as a threat to the wild populations.

Frequently asked questions

Why does Cycas debaoensis look like a fern?

Because its leaves are divided two or three times: each leaflet is split into secondary leaflets and then into narrow segments. Among Cycas, only Cycas multipinnata shares this feature.

How can it be told from Cycas multipinnata?

By its more numerous, shorter leaves (3 to 15, against 1 or 2 very long ones), its narrower, thicker leaflets and its larger megasporophylls. On young plants the difference is hard to see, and plants in cultivation are sometimes mislabelled.

How cold-hardy is it?

Moderately, as far as is known. A Californian garden reports brief dips to about −4 °C (the mid-20s °F) without damage; a US extension service gives zone 9b and an unconfirmed −8.3 °C (17 °F). In the UK it should be kept frost-free under glass.

Does it need limestone?

Not as far as anyone has shown. It grows on limestone hills in the wild, but no source shows that it needs an alkaline mix in cultivation; what matters, according to growers, is very sharp drainage.

Is it endangered?

Yes. The IUCN lists it as Critically Endangered, it is a first-class protected plant in China, and its wild populations have been heavily depleted by collecting and habitat loss.

Can it be bought legally?

Yes, if the plant or seed comes from cultivation and the CITES and national rules are respected. Plants of wild origin should always be refused.

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.

Sources

Reference sites

The World List of Cycads (version 2026.08.15), Cycas debaoensis: https://cycadlist.org/scientific_name/116 — author, protologue, type (Zhong 8762, Debao County, 850 m, 1997), synonym Cycas panshuiensis, distribution (Guangxi), IUCN status (CR A4cd), etymology, references. Checklist of the IUCN Cycad Specialist Group, reliable; consulted on 21 October 2026.
GBIF, World Checklist of Vascular Plants (Cycas debaoensis): https://api.gbif.org/v1/species/206945525 — accepted name in the World Checklist of Vascular Plants (basis of POWO), published in Acta Phytotax. Sin. 35: 571 (1997). Kew data distributed by GBIF, reliable; consulted on 31 October 2026.
Flora of China (eFloras), Cycas debaoensis: http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=210000341 — description, Chinese name, habitat, altitude, phenology, comparison with Cycas multipinnata, conservation warning. National reference flora, reliable; consulted on 21 October 2026.
GBIF (API), Cycas debaoensis: https://api.gbif.org/v1/species/2683265/iucnRedListCategory — current IUCN Red List category (CR). Reference data infrastructure; consulted on 21 October 2026.
Species+ (UNEP-WCMC), Cycas debaoensis: https://speciesplus.net/species#/taxon_concepts/15241/legal — CITES Appendix II, EU Annex B, China. Official CITES and EU database; consulted on 21 October 2026.
Commission Regulation (EU) 2026/1383: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=OJ:L_202601383 — annexes to Regulation (EC) No 338/97 in force since 29 June 2026. Official text.
The Ruth Bancroft Garden, “Plant Highlight: Cycas debaoensis” (August 2023): https://www.ruthbancroftgarden.org/plants/cycas-debaoensis/ — first male cone, identity doubt, light, watering, feeding, short frosts to the mid-twenties °F. Public garden in California, first-hand observations; consulted on 21 October 2026.
Mississippi State University Extension, Palms & Cycads for the Midsouth Landscape (P2948): https://extension.msstate.edu/publications/palms-cycads-for-the-midsouth-landscape — common name multipinnate cycad, USDA zone 9b, “reportedly hardy to 17°F”. University extension service; hardiness reported second-hand; consulted on 21 October 2026.
Royal Botanic Garden Sydney, Garden Explorer, Cycas debaoensis: https://rbgsydney.gardenexplorer.org/taxon-61772.aspx — accessions S2009-0779 (bed 51l) and S2021-0499 (bed 51s), common name “Debao Cycad”. Garden’s own catalogue (updated 1 October 2026), reliable for presence; consulted on 21 October 2026.
Fairchild Tropical Botanic Garden, Garden Explorer, Cycas debaoensis: https://fairchild.gardenexplorer.org/taxon-19934.aspx — accession 2021-0751. Garden’s own catalogue, reliable for presence; consulted on 21 October 2026.
Montgomery Botanical Center, living collection catalogue (BG-BASE “Montgomery – Cycads”, hosted by RBGE): https://www.montgomerybotanical.org/research/living-collection/ — eight accessions (20030031 to 20030035, 20080462, 20190571, 20190572, 20200214). Garden’s own catalogue, reliable for presence; consulted on 19 October 2026.
BGCI PlantSearch: https://plantsearch.bgci.org/ — gardens declaring the species (3 in the United Kingdom, about twenty in the United States, 4 in Australia). Global database of garden lists, undated per garden: a listing does not prove a living plant; consulted in October 2026.
Trebrown Nurseries, Cycas debaoensis: https://www.trebrown.com/plant_info.php?species=Cycas+debaoensis — common name “Multipinnate Cycad”, USDA zone 9b. Specialist nursery; commercial rating; consulted on 21 October 2026.
Jungle Music, “Cycas panzhihuaensis x Cycas debaoensis” (March 2023): https://junglemusic.com/2023/03/cycas-panzhihuaensix-x-cycas-debaoensis/ — hybrid offered in the trade. Californian specialist nursery; commercial source, used only to show that the hybrid is sold.
Tropicamente forum, “Cycas bifida e Cycas debaoensis” (2010–2018): https://www.tropicamente.it/forums/topic/cycas-bifida-e-cycas-debaoensis/ — young plants kept indoors and divided leaves from the first leaf (2010), vigour of a revoluta × debaoensis hybrid (2010), leaf damage in Ravenna (2014), rot in Ragusa (2018). Italian growers’ forum, cited anonymously.
ASPCA Animal Poison Control, Sago Palm: https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/sago-palm — toxicity of Cycas revoluta to dogs, cats and horses. Veterinary poison control centre; genus-level information.

Bibliography

Zhong, Y.C. & Chen, C.J. (1997). [Original description of Cycas debaoensis.] Acta Phytotaxonomica Sinica 35(6): 571. [Protologue; reference taken from The World List of Cycads and Hill (2008).]
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, habitat, phenology, conservation; consulted on eFloras.]
Hill, K.D. (2008). The genus Cycas (Cycadaceae) in China. Telopea 12(1): 71–118. doi:10.7751/telopea20085804 [Description, key, section, distribution, history, conservation.]
Yang, Y. & Ferguson, D.K. (2022). Lectotypification of Cycas debaoensis (Cycadaceae). PhytoKeys 211: 75–80. doi:10.3897/phytokeys.211.93650 [Type sheets, lectotype PE00047578, first-class protection in China.]
Tang, W. (2010). Cycas debaoensis. The IUCN Red List of Threatened Species 2010: e.T42038A10635002. doi:10.2305/IUCN.UK.2010-3.RLTS.T42038A10635002.en [Previous assessment, CR A4cd according to The World List of Cycads; reference checked on Crossref.]
Bösenberg, J.D. (2023). Cycas debaoensis. The IUCN Red List of Threatened Species 2023: e.T42038A68899343. doi:10.2305/IUCN.UK.2023-1.RLTS.T42038A68899343.en [Current assessment, CR; reference checked on Crossref, category confirmed by GBIF.]
Broome, T. (2006). Growing Cycas debaoensis in Central Florida. Cycad Newsletter 29(1): 13; and Holzman, G. (2006). Cycas debaoensis cultivation in Hawaii. Cycad Newsletter 29(1): 12. [Listed by The World List of Cycads; members-only publication.]
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.]