Cycas candida

Cycas candida is a cycad with dark green foliage and white, waxy seeds that grows on the rocky granite slopes of the Rollingstone district, north of Townsville, in Queensland, Australia. Recognised as distinct only in 2001 and described by Ken Hill in 2004, this species of the genus Cycas looks at first sight like Cycas media, but its white, bloomy seeds, which give it its name, link it to the group of blue cycads of Queensland. Its range is tiny, and the IUCN lists it as Endangered.

Key facts about Cycas candida

  • Accepted name: Cycas candida K.D.Hill (2004), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: none; older collections from the same district had been referred to Cycas media
  • Family: Cycadaceae, order Cycadales
  • Common names: none attested in English
  • Natural range: Australia, Queensland: the Rollingstone district north of Townsville, and a few kilometres north and south of it
  • IUCN status: Endangered (EN, criteria B1ab(iii,v)+2ab(iii,v)), assessment by J. D. Bösenberg (2022), EN according to GBIF
  • CITES and other protection: CITES Appendix II (listing of the whole family; seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: no data; to be kept frost-free (see Cold hardiness)
  • Light and soil: full sun; in the wild, skeletal, gritty sandy soils on steep slopes of granite boulders
  • Habit and adult size: trunk 1 to 3 m, with thick, corky bark; leaves 80 to 145 cm long
  • In the UK, US and Australia: declared in BGCI PlantSearch by James Cook University (Townsville) and San Diego Botanic Garden; no record in the UK
  • Toxicity: not studied for the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas candida

The decisive features are the moderately keeled, dark green leaves, the thick, keeled leaflets with slightly recurved margins, the soft cataphylls (the scales that protect the growing point) covered in thick orange felt and, above all, the white seeds coated in a waxy bloom. According to the original description (Hill 2004):

  • Trunk: 1 to 3 m tall, not strongly swollen at the base, with thick, corky bark.
  • Leaves: deep green, semi-glossy, 80 to 145 cm long, moderately keeled (opposite leaflets set at 90 to 130° to each other), with 180 to 300 leaflets; orange felt shed as the leaf expands; rachis usually ending in a spine 3 to 30 mm long.
  • Petiole: 17 to 40 cm long, hairless, spiny along 5 to 90% of its length; the lowest leaflets do not grade into spines.
  • Leaflets: 180 to 230 mm long, much paler beneath, set at 55 to 65° to the rachis, narrowed to 3 to 4 mm at the base, slightly keeled, with slightly recurved margins; midrib flat above, raised and wide beneath.
  • Cataphylls: linear, soft, hairy or densely floccose, persistent.
  • Male cones: ovoid, orange, about 40 cm long and 14 cm across.
  • Megasporophylls (the fertile leaves of female plants): 22 to 32 cm long, with grey or brown down that is shed; 2 to 6 hairless ovules; blade lanceolate, 60 to 90 mm by 24 to 35 mm, regularly toothed with 36 to 44 small lateral spines 1 to 3 mm long, and a terminal spine 15 to 29 mm long.
  • Seeds: flattened ovoid, 36 to 39 mm by 29 to 33 mm; fleshy coat orange-brown, strongly bloomy, 3 to 5 mm thick, with no fibrous layer or spongy tissue.

Herbarium labels written since the description show some variation: collectors in 2011 noted plants with or without petiole spines, “bluey glaucous or just green”, some covered in a rusty felt, and in 2004 one plant had blue-glaucous new fronds and another green ones.

Hybrids

No natural or garden hybrid is documented in the sources consulted.

Possible confusion

Hill (2004) notes that Cycas candida looks at first sight like Cycas media, the large cycad of the Queensland coast. It differs in its soft, floccose cataphylls, its narrower, keeled leaflets with recurved margins, and its white ovules and seeds. These features place it near Cycas cairnsiana and its group; within that group it forms, with Cycas ophiolitica and Cycas megacarpa, a small set of species with similar cataphylls and keeled but often green leaves. Cycas cairnsiana is told at once by its leaflets only 2 to 3 mm wide, rolled under and pale blue.

Taxonomy

Cycas candida is accepted by The World List of Cycads; POWO could not be consulted directly. Ken Hill described it in 2004 in “Cycas candida (Cycadaceae), a new species from Queensland together with an extension of range and amended description of Cycas yorkiana”, Telopea 10(2): 607–611. According to the original description, the type was collected at Rollingstone on 15 October 2001 by Hill, Leonie Stanberg and N. Liu (no. 5671); the holotype is in Sydney (NSW), with isotypes in Brisbane, Canberra, Guangzhou (IBSC), Kew, New York and Beijing (PE). The database of the National Herbarium of New South Wales, as published through GBIF, dates the same collection to 5 August 2001 and describes the site as open grassy woodland on a steep north-east-facing slope, on skeletal sandy loam over acid volcanic rock: the two sources differ, and the original publication has been followed here.

Hill linked the species to the group of Cycas cairnsiana, which he then called subsection Cairnsianosae (Hill 1998) and had described in 1996 as a series of subsection Endemicae. He also noted that Cycas megacarpa, previously placed with Cycas media because of its green leaves and broad, flat leaflets, belongs rather to this same set. No change of name has affected the species since its description.

Etymology and history

The epithet candida means “white” and refers to the white seeds (Hill 2004, who gives it as Greek, although the word is Latin; Haynes 2022). Plants from the Rollingstone district were collected as early as 1981 by J. R. Maconochie, who noted a burnt area with burnt fruit and fallen seed, and in 1996 by Hill on the Paluma road, but their identity remained uncertain: the population was recognised as a distinct species only in 2001. Hill explains that he described it to establish the name and give conservation authorities a legitimate name for licensing and management.

Common names

No English common name is attested, and no Aboriginal name could be verified.

In the wild

Cycas candida is known from the Rollingstone district, north of Townsville, and a few kilometres north and south of it. Hill (2004) describes it as locally abundant in grassy woodland or grassland with scattered trees, on skeletal, gritty sandy soils on steep slopes of granite boulders. A substantial part of the population lies within what Hill called Mount Spec National Park.

Herbarium labels published through GBIF (exact localities withheld for most) add eucalypt woodland on granite boulder hills, with Eucalyptus crebra and Corymbia citriodora (2011), gritty loam over porphyry on a north-east-facing hillside about 40 km south of Ingham, where plants reached 3 to 4 m (2006), and decomposed granite (2023). Several collections from 2018 note signs of past fires, and one plant was growing in a cleared patch next to regenerating woodland.

Conservation status and regulation

Cycas candida is listed as Endangered (EN, criteria B1ab(iii,v)+2ab(iii,v)) in the assessment by J. D. Bösenberg (2022) cited by The World List of Cycads; a corrected version was later issued, and the IUCN data relayed by GBIF give the EN category (consulted on 21 October 2026). These criteria reflect a very small range and area of occupancy, with a continuing decline in habitat quality and in the number of mature plants. An earlier assessment by P. Forster (2010) exists, and the 1994 IUCN list classed it as “Lower Risk, conservation dependent” (LR/cd). Hill (2004) already stressed that its range was small and that overly frequent fires could disrupt its reproduction, even within the national park. The Red List itself could not be consulted directly.

Like every species in the genus except Cycas beddomei, Cycas candida 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.

Growing Cycas candida

In short: no growing data have been published, and the few growers’ reports concern seedlings. Seed is rarely offered, and the species is very rare in collections outside Queensland.

Outdoor and in-ground cultivation

By analogy with the other species of its group and with its granite habitat, a very free-draining soil, full sun and a dry winter are advisable; this is a deduction, not documented for the species. In Australia, James Cook University, in Townsville, close to its natural range, declares it in BGCI PlantSearch, without saying where or how it is grown. In the United States, San Diego Botanic Garden, in coastal southern California, also declares it; whether the plant is outdoors or under glass is not stated.

Container cultivation

In the United Kingdom and other temperate regions, it is a plant for a heated glasshouse. The only European report comes from Italy: in February 2015 a grower in Ravenna (Emilia-Romagna), in the Italian forum Tropicamente, wrote that three plants remained from a sowing of Cycas candida, adding that the Australian Cycas are difficult; the same grower had repeatedly lost seedlings of Cycas cairnsiana, of the same group, to rot. In France, a grower ordered seed in 2011, according to the forum Fous de palmiers, without reporting any result. The French nurseryman Simon Lavaud (Cycadales.eu, 2021), who does not name Cycas candida, recommends for the Australian Cycas a very mineral substrate, full sun, a glasshouse to lengthen the growing season, and generous watering in hot weather, reduced below 20 °C (68 °F) and stopped when nights fall below 10 °C (50 °F). 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

In short: two declarations in BGCI PlantSearch (consulted in October 2026), which show that a garden has declared the species at some point, not that a living plant is there today.

  • Australia: James Cook University, Townsville campus, declares one accession in BGCI. The species does not appear in the Garden Explorer of the Royal Botanic Garden Sydney or of the Australian Botanic Garden Mount Annan, nor in the online census of the Royal Botanic Gardens Victoria.
  • United States: San Diego Botanic Garden (Encinitas, California) declares one accession in BGCI; the species is absent from the online catalogues of Montgomery Botanical Center and Fairchild Tropical Botanic Garden.
  • United Kingdom: no record.

Outside these three countries, Singapore Botanic Gardens also declare it in BGCI. No first-hand report from a private grower in the UK, US or Australia could be read; PalmTalk and Dave’s Garden could not be consulted.

Propagation

Like all Cycas, Cycas candida is dioecious and is raised from seed. No germination data specific to the species have been published; the Ravenna report shows only that seedlings can be raised in Europe, with losses. Seeds are exempt from CITES under annotation #4; ask for seed from cultivated plants or collected under permit.

Pests and diseases

No pest or disease specific to the species is documented. In the wild, overly frequent fires are the main risk to reproduction (Hill 2004). In cultivation, scale insects, including Aulacaspis yasumatsui, can attack any Cycas, and root rot in a cold, wet substrate is the cause of loss most often reported for the Australian Cycas in Europe.

Cold hardiness

No cold-tolerance data exist for Cycas candida. It lives in tropical Queensland, and nothing suggests that it can take frost.

European experience

No result in the open ground has been published in Europe, and no dated frost episode concerns the species. The Ravenna seedlings (2015) were grown in pots, and their winter conditions are not stated; the French forum Fous de palmiers reports no growing result. In the absence of data, keep it in a pot, frost-free.

United Kingdom, United States and Australia

No cold reading and no dated growing report were found, 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 candida 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, and NC State Extension notes that cycasin is present in all parts of the plant. 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 of Cycas candida is documented in the sources consulted.

Frequently asked questions

Why “candida”?

Because the seeds are white: the epithet means “white” and refers to the waxy bloom that coats them.

Is Cycas candida a blue cycad?

Not really. Its foliage is mostly dark green, although some plants have bluish new leaves; it is the ovules and seeds that are waxy white, a feature that nevertheless links it to the blue cycads of Queensland.

How can it be told from Cycas media?

By its soft, floccose cataphylls, its narrower, keeled leaflets with recurved margins, and its white, bloomy seeds.

Is it endangered?

Yes. The IUCN lists it as Endangered (2022 assessment), because it occupies only a very small area around Rollingstone.

Where can it be seen in cultivation?

Very few gardens declare it: James Cook University in Townsville and San Diego Botanic Garden, according to BGCI PlantSearch. It is not listed by any British garden.

Can it be grown outdoors in the UK?

No, almost certainly not. No cold data exist; it is a tropical species, best kept in a heated glasshouse.

Is it poisonous?

It must be assumed so. It has not been studied, but all parts of Cycas are poisonous, especially the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Hill, K.D. (2004). Cycas candida (Cycadaceae), a new species from Queensland together with an extension of range and amended description of Cycas yorkiana. Telopea 10(2): 607–611. [Original description: description, affinities, range, habitat, conservation; full text consulted (archive.org).]
  • Hill, K.D. (1996). A taxonomic revision of the genus Cycas (Cycadaceae) in Australia. Telopea 7(1): 1–64. doi:10.7751/telopea19963040 [Series of subsection Endemicae; full text consulted.]
  • Forster, P. (2010). Cycas candida. The IUCN Red List of Threatened Species: e.T178870A7631958. doi:10.2305/IUCN.UK.2010-3.RLTS.T178870A7631958.en [Earlier assessment; reference checked on Crossref, not consulted.]
  • Bösenberg, J.D. (2022). Cycas candida. The IUCN Red List of Threatened Species 2022: e.T178870A67338812. doi:10.2305/IUCN.UK.2022-1.RLTS.T178870A67338812.en [Current assessment; corrected version e.T178870A243415605; references checked on Crossref, EN category relayed by GBIF; 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 of the epithet; cited by The World List of Cycads, text not consulted.]
  • 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: accepted name, original publication, type, range, synonyms, IUCN status; consulted directly.]