Cycas desolata

Cycas desolata is a blue-leaved cycad of north-eastern Queensland, Australia, known from a small area north-west of Charters Towers, where it grows in open ironbark woodland on thin, stony soils. This species of the genus Cycas was described in 1995 by Paul Forster, of the Queensland Herbarium, and stands out for its pale blue foliage, its leaves with relatively few leaflets and its spineless petiole. Some plants exceed 7 m in height. The IUCN lists it as Near Threatened, a category kept by a reassessment published in 2023, and Queensland protects it as a Vulnerable species.

Key facts about Cycas desolata

• Accepted name: Cycas desolata P.I.Forst. (1995), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
• Former names and synonyms: no synonym; placed under Cycas angulata by de Laubenfels and Adema (1998), a treatment not followed (see Taxonomy)
• Family: Cycadaceae, order Cycadales
• Common names: none attested, in English or in any other language
• Natural range: Australia, north-eastern Queensland, north-west of Charters Towers (North Kennedy district)
• IUCN status: Near Threatened (NT), reassessment by J. D. Bösenberg (Red List version 2023-1), NT according to GBIF, after Paul Forster’s assessment (2010, criterion D2); the Flora of Australia gives “Vulnerable, 2022” (see Conservation status)
• CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union; Vulnerable in Queensland (Nature Conservation (Plants) Regulation 2020)
• Documented hardiness: no data (see Cold hardiness)
• Light and soil: open eucalypt woodland, on shallow skeletal soils or low rocky outcrops, in full light
• Habit and adult size: trunk to 4 m, rarely 7 m or more, 15 to 25 cm across; leaves 75 to 120 cm long
• In the UK, US and Australia: Royal Botanic Garden Sydney, Australian Botanic Garden Mount Annan and James Cook University, Townsville; Montgomery Botanical Center and Naples Botanical Garden (Florida), San Diego Zoo (California); no British record
• Toxicity: no data for the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas desolata

According to Paul Forster (1995) and Ken Hill (1996), three characters together identify it: pale, dull blue foliage, leaves with relatively few leaflets (90 to 136), and a petiole entirely without spines. Its long, narrow, sharp cataphylls separate it from Cycas cairnsiana, which has the same colour. In detail, after the original description and the Flora of Australia:

• Trunk: up to 4 m tall, rarely 7 m, 15 to 25 cm in diameter.
• Leaves: 75 to 120 cm long, strongly keeled (the two rows of leaflets meeting at 30 to 50°), with 90 to 136 leaflets; the axis usually ends in a pair of leaflets; petiole hairless, 10 to 23 cm long, without spines.
• Median leaflets: 18 to 21 cm long and 3.5 to 5 mm wide, hairless, glaucous blue, set at 40 to 50°, narrowed at the base (to 70 to 80% of their maximum width), 1 to 5 mm apart, with recurved margins; midrib flat above, raised below.
• New growth: densely covered in rusty hairs, which later fall.
• Cataphylls (the scales that protect the growing point): linear-lanceolate, sharp, 3 to 4.5 cm long, with orange-brown felt at the base.
• Male cones: elongated ovoid, orange or brown, 24 to 40 cm long and 8 to 9.5 cm across; terminal spine of the microsporophylls short (3 to 4 mm).
• Megasporophylls (the fertile leaves of female plants): 13 to 24 cm long, with rusty felt at the base only and glaucous blue elsewhere, bearing 2 to 6 ovules (often 4); blade broadly triangular, 28 to 32 mm long and 20 to 25 mm wide, barely toothed; terminal spine 5 to 15 mm long.
• Seeds: ovoid, 35 to 39 mm long and 32 to 35 mm wide, green then purplish yellow when ripe, heavily bloomed.

Paul Forster also stressed the unusual length of the male cones (up to 40 cm) compared with the other Queensland Cycas, and the size of some plants: he measured one of more than 7 m at the type locality, a rare height among the cycads of that state. Later herbarium labels published through GBIF record plants “occasionally to 8 metres” (1994) and, at a granite site, “some cycads to 8–9 m tall” (2006).

Hybrids

No natural or garden hybrid is documented. Neither Hill’s revision (1996) nor the Flora of Australia mentions one for this species.

Possible confusion

• Cycas cairnsiana, the most similar in its blue colour: soft cataphylls, short teeth at the base of the petiole, more numerous leaflets (180 to 280) that are shorter and narrower (8 to 18 cm by 2 to 3 mm), and a longer megasporophyll blade (40 to 70 mm); the two species have separate ranges.
• Cycas platyphylla, of the same group: blue foliage that turns grey-green, 120 to 260 flat, broader leaflets (4 to 6 mm), clearly toothed megasporophylls.
• Cycas cupida, described in 2001 from more than 200 km to the south: 174 to 240 leaflets not narrowed at the base, much longer cataphylls (70 to 95 mm), felted along their whole length, and thicker male cones.
• Cycas couttsiana, another blue cycad of northern Queensland, with soft cataphylls and grey-white down on the new growth.

Taxonomy

Cycas desolata is accepted by The World List of Cycads; POWO could not be consulted directly. Paul Forster described it in 1995 in Austrobaileya (volume 4, pages 345 to 352), from plants that Hill’s key (1992) placed under Cycas cairnsiana. In 1996, Ken Hill placed it in series Cairnsianosae of subsection Endemicae (section Cycas), which brings together the Australian cycads with strongly glaucous foliage, a continuous hypodermis in the leaflets and small to medium, ovoid male cones. In 2001, Paul Forster counted six species in it: Cycas cairnsiana, Cycas couttsiana, Cycas cupida, Cycas desolata, Cycas ophiolitica and Cycas platyphylla.

De Laubenfels and Adema (Blumea, 1998) reduced the name to a synonym of Cycas angulata, within a very broad concept of that species (page 363). Neither the Flora of Australia nor The World List of Cycads follows this treatment; they cite it only as a reference for synonymy. In 2025, Montgomery Botanical Center announced a genomic study of the “Cycas cairnsiana group” to clarify the boundaries between these closely similar species.

Etymology and history

The epithet comes from the Latin desolatus, “desolate”, “forsaken”: according to the original description, it refers to the ruinous or desolate nature of the habitat where the plant grows. The World List of Cycads, following Haynes (2022), also translates it as “isolated”.

Late in 1993, Rod Fensham, of the Queensland Herbarium (BRI), drew Paul Forster’s attention to an unknown population of cycads north-west of Charters Towers; Forster visited it early in 1994 and described the species the following year. The type, a male plant, was collected on 27 January 1994 (Forster 14671B, holotype at BRI). To limit poaching, the author deliberately did not publish the exact locality. Herbarium labels published through GBIF under the name Cycas desolata include collections made before the species was named, by D. G. Fell in 1989 and by Ken Hill and L. Stanberg in 1991.

Common names

No common name is attested for this species, in English or in any Aboriginal language, in the sources consulted.

In the wild

Cycas desolata is known only from a small region north-west of Charters Towers, in north-eastern Queensland. Paul Forster saw at least two populations, scattered over about 40 km², with more than a thousand plants; the online Flora of Australia speaks of a single stand. In 2025, Montgomery Botanical Center reported that access to the type locality had been restricted, but that its team had found a new population, “expanding its known range beyond the previously single recorded population”.

According to the original description, the plants grow in open woodland on shallow skeletal soils or low rocky outcrops, under Eucalyptus erythrophloia and an ironbark (Eucalyptus crebra or Eucalyptus xanthoclada); the Flora of Australia sums up the habitat as “flat country in open ironbark woodland”. Herbarium labels made between 1989 and 2025 widen the picture: grassy ironbark woodland on skeletal sandy soil over rhyolitic volcanic rock (1991), granite boulder slopes (2006), red sandy plains and gravelly hills (2011), shallow gravelly soils over metamorphic or igneous rock and basalt ridges (2021), and, in 2025, open woodland on granite and basalt hills between about 630 and 840 m. In February 2024, a team including Montgomery botanists recorded a “large population” of more than 300 plants on rocky slopes in seasonally dry, semi-open forest. During Forster’s visit in 1994, a long drought prevented him from recording the other associated species. The pollinator, phenology and seed dispersers of the species are not documented.

Conservation status and regulation

Cycas desolata is listed as Near Threatened (NT) by the IUCN: J. D. Bösenberg’s reassessment was published in Red List version 2023-1 (reference checked on Crossref), and the IUCN data relayed by GBIF give it the NT category (consulted on 21 October 2026). The first assessment, by Paul Forster, published in 2010, used criterion D2 (very few locations), which The World List of Cycads still displays. The online Flora of Australia, whose profile was updated in December 2025, states instead “IUCN Red List: Listed as Vulnerable, 2022”; no 2022 assessment could be found, and the Red List itself could not be consulted directly, so this divergence remains unexplained. In Queensland, the species is listed as Vulnerable under the Nature Conservation (Plants) Regulation 2020 (November 2022 list).

In 1995, Paul Forster considered the population little threatened by its landowner but exposed to poaching, the plant being highly ornamental; all known populations were then on private grazing land, and he proposed the code 2V (vulnerable) of the Australian rare plant system. Ken Hill (1996) gave the same code, noting small populations on pastoral land. In 2025, Montgomery Botanical Center wrote that Cycas cupida and Cycas desolata are “absent from most collections” and “on the brink of being listed as critically endangered”, and that the blue cycads of northern Queensland have declined through the collection of plants and seed; this comes from a garden newsletter, not from a published assessment.

Like every species in the genus except Cycas beddomei, Cycas desolata 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 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, and ask for proof that the plant was raised in cultivation.

Growing Cycas desolata

In short: no institution has published growing advice specific to the species. A specialist nurseryman ranks it among the “difficult” Australian Cycas in Europe; its habitat points to full sun, a thin, very free-draining soil and a long dry season. Outside warm climates it is a plant for a pot under glass.

Outdoor and in-ground cultivation

No dated growing report has been found. Its natural setting, thin, well-drained soils in a very bright open woodland with a long dry season in the tropics, suggests a plant for full sun, watered sparingly; this is a deduction from the habitat, not a growing result. In a 2021 note on the basics of growing Australian Cycas in a European climate, the French nurseryman Simon Lavaud (Cycadales.eu) places Cycas desolata among the “difficult” species, with Cycas angulata, Cycas cairnsiana, Cycas cupida and Cycas couttsiana, and says that it grows “on sandy soils”; the original description speaks instead of shallow skeletal soils and low rocky outcrops, although one 1991 herbarium label does mention “skeletal sandy soil”. The note reports no growing result with the species. A specialist cycad nursery in Katherine, in the Northern Territory, held plants originally collected in the wild, from which herbarium vouchers were taken in 2015 (GBIF).

Container cultivation

In the United Kingdom and other temperate regions, it is a plant for a large pot under glass. Simon Lavaud’s general advice for the Australian Cycas, not specific to this species, is a very mineral substrate, the brightest possible position, a glasshouse even if unheated 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), because of the risk of root rot. On the French forum Fous de palmiers, the name appears only in 2022, in a list of cycads that an amateur found beautiful but whose hardiness he did not know: this is neither a cultivated plant nor a growing result. The Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published no observation on Cycas desolata, so no Mediterranean experience can be passed on.

In cultivation in the UK, US and Australia

Each source below is a catalogue entry or a declaration, not proof that a plant is alive today. Most accessions are recent and of wild origin.

• Australia: the Royal Botanic Garden Sydney holds accession S2022-0443 (six plants, wild origin; Garden Explorer, updated 1 October 2026), and the Australian Botanic Garden Mount Annan three accessions of wild origin, A2022-19543 (five plants), A2024-21884 and A2024-23143 (Garden Explorer, updated 15 October 2026). James Cook University, in Townsville, declares the species in BGCI PlantSearch.
• United States: the online catalogue of Montgomery Botanical Center (Coral Gables, Florida), which grows its cycads in the open, lists seven accessions, all with numbers dating from 2024; the garden’s 2025 newsletter explains that seed of Cycas desolata was collected in the wild during an expedition to northern Queensland (herbarium specimens from this trip are dated February 2024), half of it raised in Australia and half added to Montgomery’s living collections to build “assurance colonies”. BGCI PlantSearch also lists Naples Botanical Garden (Florida) and San Diego Zoo Botanical Gardens (California), without saying whether the plants grow outdoors or under glass.
• United Kingdom: no record in BGCI PlantSearch or in the British garden catalogues consulted.

In Europe, BGCI lists a single declaration, from a garden at Saint-Gilles, in the south of France, with no detail on the plants or their placement. No 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 desolata is dioecious: a male and a female plant are needed for fertile seed. No germination data specific to the species have been published. Seeds are exempt from CITES under annotation #4; ask for seed from cultivated plants or from documented conservation programmes, as the species is threatened by collecting.

Pests and diseases

No pest or disease specific to the species is documented. Cycad scales, including the Asian cycad scale, Aulacaspis yasumatsui, can affect all cultivated species, and the Australian blue cycads are prone to root rot in a cool, wet substrate (Lavaud 2021). A 2025 herbarium label notes young leaves flushing after a fire and “under some attack from insect larvae” in the wild.

Cold hardiness

No cold-tolerance data exist for Cycas desolata. Its range lies in the dry tropics of north-eastern Australia, at about 20° south, at altitudes recorded on herbarium labels between about 520 and 840 m; nothing allows us to say that it tolerates frost.

European experience

No growing result has been published in Europe, in the open ground or in a pot. Searches of the French forum Fous de palmiers and the Italian forum Tropicamente found no report of cold tolerance, and no dated frost event concerns it. In the absence of data, grow it under glass, frost-free and dry in winter.

United Kingdom, United States and Australia

No cold reading and no growing report were found. The documented plantings are in subtropical or tropical regions (Sydney, South Florida, Townsville, San Diego); apart from Montgomery, which grows its cycads in the open, their placement is not stated, and no observation of these plants in winter has been published. No USDA zone can be given without a documented trial.

Toxicity and precautions

No toxicity analysis specific to Cycas desolata 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. North Carolina State University notes that cycasin is present in all parts of the plant, and 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. Until proven otherwise, treat the plant as poisonous: wear gloves to handle the seeds and their fleshy coat, 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

No traditional use specific to Cycas desolata has been found in the sources consulted.

Frequently asked questions

Where does Cycas desolata grow?

Only in north-eastern Queensland, Australia, north-west of Charters Towers, in open eucalypt woodland on thin, stony soils.

Why is it called desolata?

From the Latin desolatus, “desolate”: Paul Forster chose the name for the ruinous, forsaken look of the habitat where the plant grows.

How can it be told from Cycas cairnsiana?

By its cataphylls and leaflets. Cycas desolata has long, sharp cataphylls, a spineless petiole and fewer, longer leaflets (90 to 136); Cycas cairnsiana has soft cataphylls and 180 to 280 very narrow leaflets.

Is it endangered?

Moderately, according to the IUCN, which lists it as Near Threatened after the 2023 reassessment. Queensland lists it as Vulnerable, and the Flora of Australia also gives Vulnerable.

Can it be grown outdoors in the UK?

No, on the evidence available. No cold tolerance has been documented; it is grown in a pot under glass, frost-free and dry in winter.

Is it easy to grow?

No. A specialist nurseryman ranks it among the “difficult” Australian Cycas, and no growing result has been published.

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

• The Simon Lavaud Method: Grafting Cycads onto Cycas revoluta to Grow Difficult Species: a general article on growing the Australian Cycas in Europe, not about Cycas desolata, which it does not mention. It explains why these cycads often fail on their own roots under glass, rotting in cool, wet conditions, and how the French nurseryman grafts them onto Cycas revoluta; his examples are Cycas couttsiana and the Thai Cycas siamensis “Silver”.
• Watering Cycads: Common Mistakes and How to Avoid Them
• How to Grow Cycads from Seed: Germination, Seedling Care and Propagation Setup

Sources

Reference sites

• The World List of Cycads (version 2026.08.15), Cycas desolata: https://cycadlist.org/scientific_name/117 — author, original publication, IUCN status NT (D2, Forster 2010), synonymy of de Laubenfels and Adema (page 363), etymology. Checklist of the IUCN Cycad Specialist Group, reliable; consulted on 3 October 2026 (unreachable on 21 October 2026).
• Flora of Australia, Cycas desolata: https://profiles.ala.org.au/opus/foa/profile/Cycas%20desolata — description, diagnostic features, distribution (“a single stand”), habitat, “IUCN Red List: Listed as Vulnerable, 2022”, Queensland Vulnerable status. National flora (after Hill 1998), reliable; profile updated on 8 December 2025, consulted on 21 October 2026.
• GBIF (API), Cycas desolata: https://api.gbif.org/v1/species/2683285/iucnRedListCategory — current IUCN Red List category (NT). Reference data infrastructure relaying the Red List; consulted on 21 October 2026.
• GBIF, occurrences of Cycas desolata: https://www.gbif.org/occurrence/search?taxon_key=2683285 — labels of the type collection (1994) and of collections from 1989 to 2025 (habitats, substrates, altitudes, heights, a population of more than 300 plants in 2024); vouchers from a nursery in Katherine (2015). Primary herbarium data; consulted on 21 October 2026.
• Species+ (UNEP-WCMC), Cycas desolata: https://speciesplus.net/species#/taxon_concepts/28719/legal — CITES Appendix II (family listing, annotation #4), EU Annex B. Official CITES and EU database.
• 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.
• Palm and Cycad Society of Australia (PACSOA), Cycas desolata: https://pacsoa.org.au/wiki/index.php?title=Cycas_desolata — extracts from the original description (discovery, distinguishing features, plant over 7 m, at least two populations, etymology), text and photographs by P. I. Forster (Palms & Cycads 49, 1995). Specialist society; consulted on 21 October 2026.
• Simon Lavaud (2021), “Quelques données sur les bases de la culture des Cycas australiens en climat européen”, Cycadales.eu: https://cycadales.eu/wp-content/uploads/2021/04/Bases-de-la-culture-des-Cycas-australiens.pdf — Cycas desolata in the “difficult” class, “on sandy soils”; general advice for the Australian Cycas. Note by a specialist nurseryman (in French); full text consulted.
• Montgomery Botanical News 33(1), spring–summer 2025, “The Search for Australia’s Blue Cycads”: https://www.montgomerybotanical.org/wp-content/uploads/2025/06/Australia2025.pdf — new population of Cycas desolata, restricted access to the type locality, absence from most collections, seed collected for assurance colonies. Botanic garden publication.
• Montgomery Botanical Center, living collection catalogue (BG-BASE “Cycads” dataset): https://www.montgomerybotanical.org/research/living-collection/ — seven accessions of Cycas desolata (2024). Garden’s own catalogue; consulted on 21 October 2026.
• Royal Botanic Garden Sydney, Garden Explorer, Cycas desolata: https://rbgsydney.gardenexplorer.org/taxon-206861.aspx — accession S2022-0443 (six plants), wild origin. Garden’s own catalogue (updated 1 October 2026).
• Australian Botanic Garden Mount Annan, Garden Explorer, Cycas desolata: https://australianbg.gardenexplorer.org/taxon-206861.aspx — three accessions of wild origin (2022 and 2024). Garden’s own catalogue (updated 15 October 2026).
• BGCI PlantSearch: https://plantsearch.bgci.org/ — Mount Annan, James Cook University, Royal Botanic Garden Sydney, Naples, San Diego Zoo and a garden at Saint-Gilles (France) declaring the species. Global database of garden lists (declarations, not verified inventories); consulted on 21 October 2026.
• Fous de palmiers forum, message of 6 February 2022: https://www.fousdepalmiers.fr/html/forum/viewtopic.php?p=502442#p502442 — the name in an amateur’s wish list, with no plant in cultivation. Growers’ forum (in French); cited only to show the absence of growing reports.
• 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.
• NC State Extension Plant Toolbox, Cycas revoluta: https://plants.ces.ncsu.edu/plants/cycas-revoluta/ — cycasin present in all parts of the plant. University extension service; genus-level information.

Bibliography

• Forster, P.I. (1995). Cycas desolata (Cycadaceae), a new species from north Queensland. Austrobaileya 4(3): 345–352. doi:10.5962/p.365826 [Original description: description, type, habitat, population size, conservation, etymology; full text consulted (BioStor).]
• Hill, K.D. (1992). A preliminary account of Cycas (Cycadaceae) in Queensland. Telopea 5(1): 177–206. doi:10.7751/telopea19924964 [Key in which the plants keyed out to Cycas cairnsiana; reference cited by Forster (1995).]
• Hill, K.D. (1996). A taxonomic revision of the genus Cycas (Cycadaceae) in Australia. Telopea 7(1): 1–64. doi:10.7751/telopea19963040 [Series Cairnsianosae, key, conservation code 2V; full text consulted.]
• de Laubenfels, D.J. & Adema, F. (1998). A taxonomic revision of the genera Cycas and Epicycas gen. nov. (Cycadaceae). Blumea 43: 351–400. [Synonymy with Cycas angulata, page 363; reference taken from The World List of Cycads.]
• Forster, P.I. (2001). Cycas cupida (Cycadaceae), a new species from central Queensland. Austrobaileya 6(1): 153–160. doi:10.5962/p.299661 [Comparison with Cycas cupida; six species in series Cairnsianosae; full text consulted.]
• Forster, P. (2010). Cycas desolata. The IUCN Red List of Threatened Species 2010: e.T41959A10584588. doi:10.2305/IUCN.UK.2010-3.RLTS.T41959A10584588.en [First assessment, NT (D2), cited by The World List of Cycads; reference checked on Crossref, page not consulted.]
• Bösenberg, J.D. (2023). Cycas desolata. The IUCN Red List of Threatened Species 2023: e.T41959A68899597. doi:10.2305/IUCN.UK.2023-1.RLTS.T41959A68899597.en [Current assessment; reference checked on Crossref, NT 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, synonyms, IUCN status; consulted directly.]