Cycas angulata

Cycas angulata is the most robust Cycas in Australia: this cycad of the southern Gulf of Carpentaria forms, near Borroloola in the Northern Territory, real woodlands dominated by its trunks, which commonly reach 5 m and exceptionally 12 m. Described as early as 1810 by Robert Brown, it is one of the first two species of the genus Cycas named from Australia. Its keeled leaves with narrow leaflets, bluish when they emerge and then greyish green, and its very large seeds set it apart from the other Australian Cycas. The IUCN lists it as Least Concern (2022).

Key facts about Cycas angulata

  • Accepted name: Cycas angulata R.Br. (1810), accepted by The World List of Cycads (version 2026.08.15) and by the Australian Plant Census (according to the Flora of Australia); POWO could not be consulted directly
  • Former names and synonyms: no synonym of its own; the revision by de Laubenfels and Adema (1998) included about a dozen Australian species now kept separate (see Taxonomy)
  • Family: Cycadaceae, order Cycadales; section Cycas, subsection Endemicae, series Angulatosae (Hill 1996)
  • Common names: “Angular Cycas”, a trade name used by a US nursery (see Common names)
  • Natural range: Australia, Northern Territory (lower reaches of the Wearyan, Foelsche and Robinson rivers, near Borroloola) and Queensland (Bountiful Islands, Gulf of Carpentaria)
  • IUCN status: Least Concern (LC); assessment by J. D. Bösenberg published in 2022, after that of K. D. Hill (2010)
  • CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: no data (see Cold hardiness)
  • Light and soil: open grassy savanna and grassland, often near streams, on sandy alluvium on flat ground
  • Habit and adult size: trunk 5 m, rarely 12 m, 15 to 25 cm across; leaves 1.1 to 1.7 m long
  • In the UK, US and Australia: in the US at Montgomery Botanical Center (two accessions), with Fairchild, San Diego Botanic Garden and the National Tropical Botanical Garden in BGCI; in Australia at the George Brown Darwin Botanic Gardens (photographs, 2016) and, in BGCI, Adelaide, the Hunter Region and Noosa; no UK garden found
  • Toxicity: seeds rich in toxins, analysed in 2026; treat it as poisonous (see Toxicity and precautions)

How to recognise Cycas angulata

Cycas angulata is recognised by its stature, the greatest among Australian Cycas, by its clearly keeled leaves with very numerous narrow leaflets, and by its long megasporophylls carrying many large seeds. The following description is that of Ken Hill (1992) and the Flora of Australia:

  • Trunk: up to 5 m, rarely 12 m, 15 to 25 cm across.
  • Leaves: 110 to 170 cm long, keeled (the two ranks of leaflets form an angle of 90 to 135°), with 180 to 320 leaflets; petiole 28 to 52 cm long, spiny over 30 to 90% of its length.
  • Median leaflets: 14 to 23 cm by 4.5 to 6.5 mm, inserted at 40 to 60° on the rachis, spaced 6 to 9 mm apart, with recurved margins; bluish when they emerge, then greyish green and glossy.
  • Young growth: covered in dense white and orange down; cataphylls prickly, up to 13 cm long, densely orange-felted.
  • Male cones: almost globular, 20 to 25 cm long and 12 to 15 cm across, orange; terminal spine of the microsporophylls fine and upturned, 20 to 30 mm.
  • Megasporophylls: 25 to 50 cm, carrying 6 to 12 ovules; narrowly triangular blade of 50 to 105 mm, finely and regularly toothed, terminal spine 12 to 38 mm.
  • Seeds: egg-shaped, green then orange, without bloom, 45 to 60 mm by 40 to 50 mm; among the largest in the genus in Australia.

Ken Hill also described the anatomy of the leaflets: a continuous layer of thick-walled cells beneath the epidermis, stomata sunk in deep, closed pits, and a very thick cuticle, features of a plant adapted to a long dry season.

The PACSOA wiki, the online encyclopaedia of the Palm and Cycad Societies of Australia, gives a mature average height of 10 m, with reports of taller plants; this is more than the figures of Hill and the Flora of Australia, which are followed here.

Hybrids

No natural hybrid involving Cycas angulata is reported in Hill’s revision (1996), which nevertheless records several hybrid populations between other Australian Cycas. No garden hybrid is documented.

Possible confusion

Within its range, the most likely confusion is with the other member of the same series:

  • Cycas brunnea, from around Lawn Hill Creek (Queensland) and Wollogorang (Northern Territory): similar habit and seeds, the same dark brown down, but broader leaflets (6 to 7.5 mm), flatter and more widely spaced (9 to 13 mm), bluer and bloomed foliage and seeds, and smaller seeds (36 to 39 mm). The Flora of Australia notes that the Northern Territory populations of Cycas brunnea have been treated as Cycas angulata;
  • Cycas megacarpa, from eastern Queensland, also with keeled leaves and prickly cataphylls, but with a slender trunk (under 15 cm across), shorter leaves (70 to 110 cm) and short cataphylls;
  • Cycas media, from eastern Queensland, with almost flat leaves and hairless leaflets whose margins are barely recurved.

Taxonomy

Cycas angulata is accepted by The World List of Cycads; POWO could not be consulted directly. Robert Brown published it in 1810 in his Prodromus florae Novae Hollandiae (page 348), at the same time as Cycas media: they are the first two Cycas described from Australia. George Bentham later reduced all the Australian species to Cycas media in 1873, and Julius Schuster still included Cycas angulata in the typical variety of Cycas media in 1932 (Hill 1996).

Ken Hill reinstated the species in his revision of the Cycas of Queensland (1992), then made it the type species of series Angulatosae, which he described in 1996 and which contains only two species, Cycas angulata and Cycas brunnea. The series belongs to subsection Endemicae of section Cycas, which groups the Australian species. It is defined by keeled leaves, more or less glaucous leaflets with recurved margins, hard, prickly cataphylls and large, almost globular male cones.

Two years later, David de Laubenfels and Frits Adema (Blumea, 1998) took a much broader view of the species, placing in its synonymy Cycas ophiolitica, Cycas platyphylla, Cycas couttsiana, Cycas brunnea, Cycas arnhemica, Cycas orientis, Cycas desolata, Cycas badensis, Cycas maconochiei, Cycas semota, Cycas tuckeri and Cycas yorkiana. This view has not been followed: the Australian Plant Census (consulted by the Flora of Australia in November 2025) and The World List of Cycads keep these species separate. If you find one of these names placed under Cycas angulata in a book from the late 1990s, this revision is the reason.

Etymology and history

The epithet angulata comes from the Latin angulatus, “angled”: it refers to the marked angle at which the leaflets are inserted on the rachis (Haynes 2022, as taken up by The World List of Cycads).

The type is a collection by Robert Brown kept at the Natural History Museum, London (holotype, BM), with an isotype at Kew. The original label is missing. According to Ken Hill, who relies on the inventory of Brown’s collections published by Groves and Moore (1989), the plant was probably collected on 3 and 4 December 1802 on Bountiful Island, near Mornington Island, in the Gulf of Carpentaria; the species was found there again in 1988 (Clarkson 7649). The World List of Cycads gives the original locality wording, “New Holland, North Coast”.

Common names

No traditional English common name is attested for this species. A US nursery (Top Tropicals) sells it as “Angular Cycas”, a translation of the epithet: this is a trade name, not a vernacular name. The names given to the plant in the Aboriginal languages of the Borroloola region were not found in the sources consulted.

In the wild

Cycas angulata lives at the southern end of the Gulf of Carpentaria, on both sides of the border between the Northern Territory and Queensland. Ken Hill knew it from the lower reaches of the Wearyan, Foelsche and Robinson rivers, near Borroloola, and from the Bountiful Islands group, further east. It grows in open grassy savanna or grassland, often near streams, on sandy alluvium on flat ground.

In the Northern Territory it forms in places woodlands where the cycads dominate; in Queensland it is less abundant and known only from the islands. The Flora of Australia gives the fruiting season as June to November, during the dry season. The pollinator and the animals that disperse the seeds are not documented for the species; the study by Lloyd and colleagues (2026) only notes that the high toxin content of the fleshy seed coat implies that any dispersing animals tolerate these toxins.

Conservation status and regulation

Cycas angulata is listed as Least Concern (LC) by the IUCN in the assessment by John Donald Bösenberg published in 2022; the previous assessment, by K. D. Hill, dates from 2010 (references checked on Crossref), and the IUCN data relayed by GBIF confirm the LC category (consulted on 21 October 2026). Ken Hill already considered it “not threatened” in 1992 and 1996. The Red List itself could not be consulted directly.

Like every species in the genus except Cycas beddomei, Cycas angulata 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 angulata

In short: no institution has published growing advice for Cycas angulata. It is grown in tropical gardens in northern Australia, and its seed circulates among European amateurs.

Outdoor and in-ground cultivation

Its natural habitat points to a plant for full sun, a tropical climate with a marked dry season and well-drained sandy soil. In the open, it is documented only in the tropics of northern Australia: a member of the French forum Fous de palmiers living in Thailand photographed it in September 2016 at the George Brown Darwin Botanic Gardens, and the PACSOA wiki shows a cultivated plant at Katherine, in the Northern Territory. No outdoor trial has been published in a Mediterranean or temperate climate.

The French nurseryman Simon Lavaud (Cycadales.eu), in a 2021 note on growing Australian Cycas in a European climate, sees Cycas angulata as the exception among the species of the Northern Territory: he rates it “difficult”, whereas all the other Northern Territory species are “very difficult”, and quotes an Australian cycad specialist for whom it grows very well in the subtropical climate of the Sunshine Coast, in Queensland, where the other Northern Territory species are very temperamental. He illustrates it with a plant grown at Nong Nooch Tropical Garden, in Thailand. These are a grower’s assessments, not trial results.

Container cultivation

In the United Kingdom and other temperate regions, its adult size and the usual slow growth of cycads make it a plant for a large heated glasshouse. Young plants can be kept in pots, in full light, in a free-draining sandy compost. On the Italian forum Tropicamente, a collector mentioned a young plant in 2013 without giving any growing conditions, and another participant observed that Australian Cycas in general are very hard to keep alive in Italy, because of low temperatures rather than humidity: an opinion about the group, not a result for this species. The Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published no observation on Cycas angulata.

In cultivation in the UK, US and Australia

In short: grown in a few gardens in the United States and Australia, apparently absent from British collections. 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, in Coral Gables, Florida, lists two accessions, which their numbers suggest date from 1985 and 2003; Fairchild Tropical Botanic Garden, San Diego Botanic Garden and the National Tropical Botanical Garden, in Hawaii, declare the species in BGCI PlantSearch.
  • Australia: plants photographed in 2016 at the George Brown Darwin Botanic Gardens (forum Fous de palmiers) and a cultivated plant at Katherine (PACSOA wiki); according to a specialist quoted by Simon Lavaud (2021), it grows very well on the Sunshine Coast, in Queensland; the Botanic Gardens of South Australia (Adelaide), the Hunter Region Botanic Gardens and the Noosa Botanic Gardens declare it in BGCI PlantSearch. It does not appear in the Garden Explorer of the Royal Botanic Garden Sydney.
  • United Kingdom: no record.

No first-hand report from a private grower in these countries could be read; PalmTalk and Dave’s Garden could not be consulted.

Propagation

Like all Cycas, Cycas angulata is dioecious: a male and a female plant are needed for fertile seed. Seed is the only documented method of propagation. In December 2009, a grower based between Belley (Ain) and Montpellier (Hérault), in France, reported on the forum Fous de palmiers that seeds of Cycas angulata germinated in ten days on a heated mat, in plastic bags filled with moist coconut chips; he added that germination in the glasshouse, where the temperature varied too much, had cost him seeds of other species through drying of the embryo.

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. Scale insects, including Aulacaspis yasumatsui, threaten all cultivated Cycas, but no attack has been reported on this species in particular.

Cold hardiness

No cold-tolerance data exist for Cycas angulata. Its whole range lies in the tropical north of Australia; nothing suggests that it can take frost.

European experience

No cultivation result has been published in Europe, in the open ground or in a pot, and no dated frost episode concerns the species. A search of the French forum Fous de palmiers and the Italian forum Tropicamente found no report of cold tolerance. The general opinion quoted above, that Australian Cycas struggle with low winter temperatures in Italy, is the only Mediterranean indication available; in the absence of data, grow it under heated glass.

United Kingdom, United States and Australia

No cold reading and no dated growing report were found, either on forums or from botanic gardens. The only known growing results come from tropical regions (Darwin, Katherine) and from gardens in southern Florida, Hawaii and coastal California that do not publish cold observations. Treat it as frost-tender; no USDA zone can be given without a documented trial.

Toxicity and precautions

Cycas angulata is one of the few Cycas whose toxins have been measured layer by layer. In 2026 Georgia Lloyd and colleagues (Annals of Botany) analysed seeds collected in the south-west of the Gulf of Carpentaria (Northern Territory). The azoxyglycosides are the most abundant toxins in every layer of the seed: cycasin dominates in the inner layers, macrozamin in the outer layers. The fleshy coat (sarcotesta) and the kernel (megagametophyte) are the most toxic parts, and the thin inner membrane the least. Contrary to what was assumed, the orange fleshy coat may therefore be as toxic as the kernel. The study also looked for BMAA, a neurotoxic amino acid.

These results confirm for the species a risk well established 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. 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

The Flora of Australia states that the kernels were eaten by Aboriginal people after careful preparation and cooking, and the PACSOA wiki describes the species as probably the cycad most often mentioned as a food source by Aboriginal people of the Northern Territory. In northern Australia, Cycas seeds were detoxified by brief or prolonged leaching in water, or by ageing, before being ground into flour (review by Asmussen 2011, after Beck 1992). The study by Lloyd and colleagues (2026) calls the species “culturally important”. These preparations must never be imitated.

Frequently asked questions

Is Cycas angulata the largest cycad in Australia?

It is the most robust Cycas in Australia, according to Ken Hill: its trunks reach 5 m and rarely 12 m, 15 to 25 cm across. Other Australian cycads outside the genus Cycas grow taller, such as Lepidozamia hopei, which can exceed 17 m.

Where does it grow?

At the southern end of the Gulf of Carpentaria: near Borroloola, in the Northern Territory, and on the Bountiful Islands, in Queensland, in grassy savanna on sandy soil.

How can it be told from Cycas brunnea?

By its narrower leaflets (4.5 to 6.5 mm), more crowded and more recurved, and by its larger seeds (45 to 60 mm), without bloom.

Why do some books merge it with other species?

Because a 1998 revision placed about a dozen Australian species under it. Current reference checklists keep them all separate.

Can it be grown outdoors in the UK?

No. No cold data exist and its whole range is tropical; it needs a heated glasshouse.

Are its seeds edible?

No, not without long and carefully controlled detoxification. Aboriginal people prepared them before eating them, but a 2026 study confirms high toxin levels, including in the orange flesh.

Is it endangered?

No. The IUCN lists it as Least Concern (2022), but like all cycads it remains covered by CITES.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Brown, R. (1810). Prodromus florae Novae Hollandiae et insulae Van-Diemen: 348. London. [Original publication; not consulted directly, reference taken from The World List of Cycads.]
  • Hill, K.D. (1992). A preliminary account of Cycas (Cycadaceae) in Queensland. Telopea 5(1): 177–206. doi:10.7751/telopea19924964 [Full text consulted.]
  • Hill, K.D. (1996). A taxonomic revision of the genus Cycas (Cycadaceae) in Australia. Telopea 7(1): 1–64. doi:10.7751/telopea19963040 [Reference revision for Australia; full text consulted.]
  • Hill, K.D. (1998). Cycadaceae. In McCarthy, P.M. (ed.), Flora of Australia 48: 597–635. CSIRO Publishing, Melbourne. [Consulted in its updated online version (profiles.ala.org.au).]
  • de Laubenfels, D.J. & Adema, F. (1998). A taxonomic revision of the genera Cycas and Epicycas gen. nov. (Cycadaceae). Blumea 43(2): 351–400. [Very broad species concept; not consulted directly for this species, cited after The World List of Cycads and the Flora of Australia.]
  • Lloyd, G.R., Holt, P., Maher, K. & Gleadow, R.M. (2026). Integrated LC/MS–MS approaches reveal toxicity differences across seed layers of Cycas angulata. Annals of Botany. doi:10.1093/aob/mcag169 [Abstract consulted.]
  • Asmussen, B. (2011). “There is likewise a nut…” A comparative ethnobotany of Aboriginal processing methods and consumption of Australian Bowenia, Cycas, Lepidozamia and Macrozamia species. Technical Reports of the Australian Museum, Online 23(10): 147–163. doi:10.3853/j.1835-4211.23.2011.1575 [First page consulted (detoxification methods after Beck 1992).]
  • Hill, K.D. (2010). Cycas angulata. The IUCN Red List of Threatened Species 2010: e.T41981A10591752. doi:10.2305/IUCN.UK.2010-3.RLTS.T41981A10591752.en [Previous assessment; reference checked on Crossref, page not consulted.]
  • Bösenberg, J.D. (2022). Cycas angulata. The IUCN Red List of Threatened Species: e.T216580894A67334546. doi:10.2305/IUCN.UK.2022-1.RLTS.T216580894A67334546.en [Current assessment (LC); reference checked on Crossref and The World List of Cycads, category confirmed by GBIF; Red List 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 [Source of the etymologies taken up by The World List of Cycads; not consulted directly.]
  • 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.]