Cycas basaltica

Cycas basaltica is a cycad of the northern Kimberley, in Western Australia, which grows only on stony basalt slopes, from the islands west of Port Warrender to around Kalumburu. Described by Charles Gardner in 1923, this species of the genus Cycas was long treated as a mere variety, Cycas media var. basaltica. Its flat leaves with broad, white-downy leaflets set almost at right angles to the midrib distinguish it from the other cycads of the region. The IUCN lists it as Least Concern (2022).

Key facts about Cycas basaltica

  • Accepted name: Cycas basaltica C.A.Gardner (1923), accepted by The World List of Cycads (version 2026.08.15); POWO could not be consulted directly
  • Former names and synonyms: Cycas media var. basaltica (C.A.Gardner) J.Schust. (1932); placed under Cycas normanbyana by de Laubenfels and Adema (1998)
  • Family: Cycadaceae, order Cycadales
  • Common names: no name specific to the species; the Royal Botanic Garden Sydney labels it “Zamia Palm” (see Common names)
  • Natural range: Western Australia, northern Kimberley (from the islands west of Port Warrender to around Kalumburu)
  • IUCN status: Least Concern (LC), assessment by J. D. Bösenberg published in 2022; LC according to GBIF
  • 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: thin red or grey clays on stony basalt slopes
  • Habit and adult size: trunk to 2 m, rarely 4 m, 15 to 23 cm across, leaves 80 to 125 cm long (Hill 1996); the original description gives a trunk of 4 to 8 feet (1.2 to 2.4 m), swollen at the base to two feet (about 60 cm) across
  • In the UK, US and Australia: grown at the Royal Botanic Garden Sydney (two wild-origin accessions); no record in the UK or the US
  • Toxicity: no data specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas basaltica

Ken Hill sums up the characters of Cycas basaltica as flat leaves with broad leaflets, set at right angles to the rachis, white-downy but not glaucous, with slightly recurved margins. The basal leaflets shrink progressively until they become spines on a short petiole. According to Hill (1996) and the Flora of Australia:

  • Trunk: up to 2 m, rarely 4 m, 15 to 23 cm across.
  • Leaves: 80 to 125 cm long, flat (rows of leaflets at 180°), with 140 to 210 leaflets, always ending in a pair of leaflets; petiole short (8 to 20 cm), grey-felted, spiny along 5 to 50% of its length, often with only a few spines towards the top.
  • Median leaflets: 9 to 18 cm by 5.5 to 9.5 mm, inserted at 70 to 80°, 6 to 13 mm apart; greyish-white down that wears off older leaves, glossy mid-green; margins flat or slightly recurved, tip acute.
  • Young growth: dense greyish-white down mixed with pale orange-brown hairs, usually persistent; cataphylls (the scales protecting the growing point) thin, 7 to 13 cm long, orange-brown felted.
  • Male cones: narrowly ovoid, 18 to 24 cm long and 7 to 9 cm across, orange to brown; sterile part of the microsporophylls curved back, terminal spine upright, 5 to 11 mm.
  • Megasporophylls (the fertile leaves of female plants): 17 to 24 cm long, brown-felted, carrying 2 to 6 ovules; sterile blade narrowly triangular, 50 to 90 mm, regularly toothed (6 to 20 teeth of 2 to 4 mm), terminal spine 20 to 35 mm.
  • Seeds: ovoid, green then yellowish, with a bloom, 27 to 31 mm by 26 to 30 mm.

Gardner’s original description (1923), based on material he admitted was “not very complete”, differs in part. He describes the plant as “Palm-like, with a stout erect trunk of 4-8 feet, swollen at the base to a diameter of two feet, otherwise 18 inches diameter, rough and dark grey” (1.2 to 2.4 m tall, about 60 cm and 45 cm across); leaves to 4 feet (about 1.2 m), hoary-downy when young, later hairless, on petioles to 8 inches (about 20 cm) whose spines are not visible on mature leaves and few on young ones; numerous rigid, linear leaflets, “hoary beneath, even when old”, with somewhat recurved margins; narrowly conical male cones; stalked megasporophylls densely rusty-felted, usually with four ovules, with an entire, lanceolate blade ending in a stiff, pungent point; and globular, hard, hairless seeds, glaucous when young. Gardner compared the species with Cycas media, from which it differs mainly by this narrow, entire megasporophyll blade, its smaller, fully globular seeds and its downy leaflets with recurved margins, and with Cycas cairnsiana, from which it differs chiefly in the number of ovules.

Two differences from Hill (1996) stand out: the trunk diameter (about 45 cm, and 60 cm at the base, against 15 to 23 cm) and the megasporophyll blade, entire according to Gardner, regularly toothed according to Hill. The sources consulted do not comment on these differences. A note by L. P. Butt reproduced on the wiki of the Palm and Cycad Societies of Australia (PACSOA, from Palms & Cycads 27, 1990) also gives trunks swollen at the base and 30 to 60 cm in diameter, with silvery new leaflets contrasting with a rusty gold-brown rachis.

Hybrids

Ken Hill (1996) reports natural hybrid populations between Cycas basaltica and Cycas lane-poolei in Western Australia: in the southern part of the Mitchell Plateau, populations form a transition between the two species. No garden hybrid is documented.

Possible confusion

  • Cycas furfuracea, from the Kimberley, its closest relative: the same short petiole with basal leaflets reduced to spines, but clearly keeled leaves, glaucous leaflets inserted at 40 to 50° and longer, narrower male cones (30 to 40 cm);
  • Cycas pruinosa, the third species of the same series, in the Kimberley: keeled leaves, narrow leaflets with recurved margins, spindle-shaped male cones more than 35 cm long;
  • Cycas lane-poolei, with which it hybridises: leaflets with flat margins and no progressive reduction at the base, cataphylls covered in thick orange wool.

Taxonomy

Cycas basaltica is accepted by The World List of Cycads; POWO could not be consulted directly. The Western Australian botanist Charles Gardner described it in 1923 in the Bulletin of the Forests Department of Western Australia (number 32, pages 30 to 32), together with Cycas lane-poolei, described in the same bulletin (the latter had already been presented in a newspaper article in 1922). Robert Pilger (1926) then ignored the Kimberley species, and Julius Schuster (1932) reduced the plant to a variety of Cycas media, as Cycas media var. basaltica. Ken Hill calls Schuster’s infraspecific hierarchies “often absurd”. John Maconochie recognised the species as distinct again in 1980, and Hill confirmed it in his 1996 revision.

Hill placed it in series Furfuraceosae, confined to the Kimberley, with Cycas furfuracea and Cycas pruinosa: basal leaflets diminishing to spines, leaves always ending in a pair of leaflets, soft cataphylls and narrow male cones. De Laubenfels and Adema (Blumea, 1998) placed it under Cycas normanbyana, a name that current checklists treat as a synonym of Cycas media, from Queensland; this treatment is not followed by The World List of Cycads.

Etymology and history

The epithet basaltica refers to the basalt rocks on which the species grows in Western Australia (Haynes 2022, taken up by The World List of Cycads).

The type is Charles Gardner’s collection no. 1490, made on 27 July 1921 on the Lawley River, in the Kimberley, and kept at the Western Australian Herbarium in Perth (PERTH); Gardner cited it as no. 1490 of the Forests Department Herbarium. He placed the species on “basalt hills near the Lawley river”, in open forest of Eucalyptus foelscheana and Eucalyptus spenceriana, with fruit in August.

Common names

No common name specific to this species is attested. The Royal Botanic Garden Sydney labels its plants “Zamia Palm”, a label it also uses for Cycas armstrongii: a general garden name, not a name for this species. No name in a Kimberley Aboriginal language was found in the sources consulted.

In the wild

Cycas basaltica is widespread in the northern Kimberley, from the islands west of Port Warrender to around Kalumburu. All known populations grow on very thin red or grey clays on stony basalt slopes. The collections cited by Hill come notably from the Bougainville Peninsula, Careening Bay, the Mitchell Plateau and the Kalumburu track. According to the note by L. P. Butt on the PACSOA wiki, the largest colonies known in 1990 were in open eucalypt country, around the bases of small hills in Drysdale River National Park.

Pollinators and seed dispersers are not documented for the species. The original description only mentions plants in fruit in August, near the Lawley River.

Conservation status and regulation

Cycas basaltica is listed as Least Concern (LC) by the IUCN in the assessment by John Donald Bösenberg published in 2022, and the IUCN data relayed by GBIF confirm the LC category (consulted on 21 October 2026). Ken Hill did not consider it threatened in 1996. The Red List itself could not be consulted directly.

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

In short: no institution has published growing advice for Cycas basaltica. It is grown at the Royal Botanic Garden Sydney, and European collectors are interested in it, but no cultivation result has been published.

Outdoor and in-ground cultivation

Its habitat (thin, stony soils, a tropical climate with a long dry season) points to a plant for full sun, in a very free-draining substrate, watered sparingly. The Royal Botanic Garden Sydney grows plants of wild origin, one of them in a numbered bed; the online catalogue does not say how they fare or whether they are protected. No outdoor trial has been published in a Mediterranean climate.

Container cultivation

In the United Kingdom and other temperate regions, it is a plant for a heated glasshouse, in a gritty, mineral compost, with full light. No account of pot culture has been found. The Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published no observation on Cycas basaltica.

In cultivation in the UK, US and Australia

In short: recorded only in Australia, at the Royal Botanic Garden Sydney.

  • Australia: the Garden Explorer of the Royal Botanic Garden Sydney (updated on 1 October 2026) lists Cycas basaltica under two accessions of wild origin, S1990-2910, in bed 65h, and S2015-1275, with several plants; their numbers suggest that they entered the collection in 1990 and 2015. The garden also declares the species in BGCI PlantSearch. It does not appear in the Garden Explorer of the Australian Botanic Garden Mount Annan or in the online census of the Royal Botanic Gardens Victoria.
  • United States: no record in BGCI PlantSearch or in the online catalogues of Montgomery Botanical Center and Fairchild Tropical Botanic Garden.
  • 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 basaltica 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.

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 basaltica. Its range, in the northern Kimberley, is entirely tropical; 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. In February 2022, a grower from Batz-sur-Mer, on the Atlantic coast of France, listed it on the French forum Fous de palmiers among the Australian Cycas whose hardiness he wanted to know; the question received no answer with figures. A search of Fous de palmiers and of the Italian forum Tropicamente found no report of cold tolerance.

United Kingdom, United States and Australia

No cold reading and no dated growing report were found, either on forums or from botanic gardens. The Sydney plants say nothing about frost tolerance, since the garden publishes no cold observation for them. Treat it as frost-tender; no USDA zone can be given without a documented trial.

Toxicity and precautions

No toxicity analysis specific to Cycas basaltica 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. 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 use specific to this species is documented in the sources consulted.

Frequently asked questions

Why is it called basaltica?

Because it grows only on basalt soils, in the northern Kimberley of Western Australia.

Is it a variety of Cycas media?

No. Schuster classed it in 1932 as Cycas media var. basaltica, but the species has been recognised as distinct since the work of Maconochie and Hill.

How can it be told from Cycas furfuracea?

By its flat, not keeled, leaves and its green, white-downy leaflets set almost at right angles, whereas those of Cycas furfuracea are glaucous and point forwards.

How hardy is it?

Unknown. No cold data have been published, and the question, asked by a French grower in 2022, went unanswered; its range is tropical.

What soil does it need?

A very free-draining, lean substrate. In the wild it grows on thin, stony clays on basalt slopes.

Is it endangered?

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

Is it poisonous?

It must be assumed so. No toxicity analysis specific to the species exists, but the Cycas studied contain dangerous toxins, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Gardner, C.A. (1923). Botanical notes. Bulletin of the Forests Department of Western Australia 32: 30–32. [Original description; full text of the description read (page 31 according to The World List of Cycads): description, habitat, type, comparison with Cycas media and Cycas cairnsiana. Primary source.]
  • Schuster, J. (1932). Cycadaceae. In Engler, A. (ed.), Das Pflanzenreich IV.1 (Heft 99). Leipzig. [Combination Cycas media var. basaltica; not 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, cited after The World List of Cycads and the Flora of Australia.]
  • Butt, L.P. (1990). [Note on Cycas basaltica.] Palms & Cycads 27. [Not consulted in the original; text reproduced on the PACSOA wiki.]
  • Bösenberg, J.D. (2022). Cycas basaltica. The IUCN Red List of Threatened Species: e.T41988A67336665. doi:10.2305/IUCN.UK.2022-1.RLTS.T41988A67336665.en [Current assessment; reference checked on Crossref and The World List of Cycads, LC category relayed 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.]