Macrozamia macleayi

Macrozamia macleayi is a cycad from south-eastern Queensland, in eastern Australia, found from the Brisbane area north to Mount Colosseum, near Miriam Vale, where it grows in the understorey of dry araucarian forest and open eucalypt forest. This species of the genus Macrozamia, described as early as 1868, was long confused with Macrozamia miquelii, and books and collections still list it under that name; it was only reinstated as a separate species in 2001. It is common and not threatened, and its cones, which warm up every day around midday, have become a model for research on pollination by thrips.

Key facts about Macrozamia macleayi

  • Accepted name: Macrozamia macleayi Miq. (1868), accepted by The World List of Cycads (version 2026.08.15) and the Australian Plant Census
  • Former names and synonyms: Macrozamia cylindrica C.Moore (1884, an illegitimate name); Macrozamia tridentata subsp. cylindrica J.Schust. (1932); long included in Macrozamia miquelii
  • Family: Zamiaceae, order Cycadales; section Macrozamia
  • Common names: no English or Aboriginal name specific to the species is recorded
  • Natural range: south-eastern Queensland, Australia, from Mount Colosseum (near Miriam Vale) to the Brisbane region, at 100 to 500 m; an old record from New South Wales is considered very doubtful
  • IUCN status: Least Concern (LC), assessment by J.D. Bösenberg dated 14 August 2020 and published in 2022
  • CITES and other protection: CITES Appendix II (annotation #4); Annex B in the European Union; “Special least concern” plant under Queensland law; not listed under the federal EPBC Act
  • Documented hardiness: no cultivation data (see Cold hardiness)
  • Light and soil: in the wild, the understorey of dry araucarian forest and open eucalypt forest; no published growing advice
  • Habit and adult size: stem underground or short, up to 35 cm tall and 30 cm across; 6 to 50 leaves 0.5 to 2 m long
  • In the UK, US and Australia: declared to BGCI by San Diego Botanic Garden and The Huntington in California, and by the System Garden of the University of Melbourne; no British garden
  • Toxicity: not documented for the species; seeds and leaves toxic throughout the genus (see Toxicity and precautions)

How to recognise Macrozamia macleayi

Macrozamia macleayi is a medium-sized cycad with straight, dark green, glossy leaves whose lowest leaflets shrink into numerous rigid spines. Jones, Forster and Sharma (2001), who redescribed the species, give the following characters.

  • Stem: usually underground, sometimes emergent, erect, columnar or barrel-shaped, up to 35 cm tall and 30 cm across, unbranched.
  • Leaves: 6 to 50 in the crown, 0.5 to 2 m long, dark green and glossy, flat in cross-section, arching; the expanded base covered in grey-brown woolly hairs; petiole 10 to 30 cm long; axis straight, not twisted or barely so.
  • Leaflets: 80 to 160 per leaf, 15 to 50 cm long and 6 to 9 mm wide, thin-textured, dark green and shiny above, with a whitish callous base and a sharp tip; the lowest ones are progressively reduced to 8 to 28 pairs of stiff spines.
  • Male cones: 1 to 5, cylindrical, 15 to 20 cm long and 3.8 to 6.5 cm across, green.
  • Female cones: 1 or 2, cylindrical to barrel-shaped, 19 to 30 cm long and 7 to 10 cm across, green, on a stalk 15 to 41 cm long; each scale ends in an upright spine 0.5 to 4.5 cm long.
  • Seeds: oblong to obovoid, 2.5 to 3.5 cm long and 1.5 to 2.5 cm wide, with orange to red flesh.

Hybrids

Yes. WildNet, the Queensland Government’s wildlife database, records a hybrid Macrozamia lucida × Macrozamia macleayi, known from a single locality in the Brisbane region. It also lists intermediate forms recorded as “Macrozamia longispina – Macrozamia macleayi” and “Macrozamia macleayi – Macrozamia mountperriensis”. No description of these plants has been published.

Possible confusion

The main confusion is with Macrozamia miquelii, under whose name the species was filed for more than forty years. According to Jones, Forster and Sharma (2001), Macrozamia macleayi has a more southerly range and differs in its glossier, thinner-textured leaflets and its narrower female cones (7 to 10 cm across, against 10 to 15 cm). Some illustrations published as Macrozamia miquelii in standard works on the Queensland flora actually show Macrozamia macleayi; the online Flora of Australia cites two of them, in Williams (1984) and in Stanley and Ross (1989).

The other species of the same group are best separated by the number of spines at the base of the leaf: Macrozamia mountperriensis and Macrozamia longispina have none. Macrozamia lucida, which shares part of its range, has broad, non-pungent leaflets, none of which turn into spines.

Taxonomy

Macrozamia macleayi Miq. is accepted by The World List of Cycads and the Australian Plant Census. The Dutch botanist Friedrich Anton Wilhelm Miquel described it in 1868 in the Archives néerlandaises des sciences exactes et naturelles (vol. 3, p. 250). The type, without collector’s name or date, came from Moreton Bay, near Brisbane; the holotype is held in Utrecht (U). Forster (1999) clarified its typification and the application of the name.

The history of the name is eventful. In 1959 L.A.S. Johnson, a cautious taxonomist, sank all the names of this group into Macrozamia miquelii, and the Flora of Australia (Hill, 1998) still treated these plants under that name. In 2001, Jones, Forster and Sharma revised the whole Macrozamia miquelii group in the journal Austrobaileya: on the basis of field observations and a partial isozyme analysis, they reinstated Macrozamia macleayi as a distinct species. The Australian Plant Census now accepts it, as does The World List of Cycads. In practice, a plant labelled “Macrozamia miquelii” that came from the Brisbane region or the hinterland of Gympie may well be Macrozamia macleayi.

Two older names belong to the species: Macrozamia cylindrica C.Moore (1884), an illegitimate name based on a collection of 1861 from “between the upper Richmond and the Clarence”, in New South Wales, and Macrozamia tridentata subsp. cylindrica J.Schust. (1932). The species belongs to section Macrozamia, the group of larger species with spiny basal leaflets.

Etymology and history

The epithet probably honours William John Macleay (1820–1891), naturalist, pastoralist and politician of New South Wales and a pillar of the Linnean Society of New South Wales, whose collections form the basis of the Macleay Museum at the University of Sydney (Jones et al., 2001; Haynes, 2022). Miquel himself wrote only that the plant grows in the Moreton Bay district, “where MacLeay probably discovered it”. The genus name Macrozamia combines the Greek makros, “large”, with the genus name Zamia.

The 1868 description was based on garden plants, not on field material. Miquel had only young, sterile plants grown in Europe: a living plant in the Utrecht botanic garden, with an ovoid trunk bearing two leaves, and leaves sent by the nurseryman Van Houtte under the name “Catakidozamia MacLeayi”, taken from plants raised from seed collected at Moreton Bay. He knew nothing of the cones and separated the species by the wool on its trunk and leaf bases and by the reddish base of its leaflets, which gave the leaf an elegant look.

Common names

No common name specific to Macrozamia macleayi is recorded in English, and no Aboriginal name is attested for it. Gardeners and botanists use the scientific name.

In the wild

Macrozamia macleayi has a disjunct range, from Mount Colosseum near Miriam Vale in the north to the Brisbane region in the south, by way of the Burnett Range and the Imbil district (Jones et al., 2001). An old record from New South Wales, based on the 1861 collection of Macrozamia cylindrica, has never been confirmed, and the authors consider it “extremely dubious”.

The plant grows between 100 and 500 m, in the understorey of dry araucarian vine forest or in open forest often dominated by Eucalyptus acmenoides, Eucalyptus crebra, Eucalyptus major, Eucalyptus microcorys and Lophostemon confertus. Pollen is shed in October and November, and ripe seeds fall in March and April.

Cones that heat up

The cones of Macrozamia macleayi are visited by a specialised thrips, Cycadothrips chadwicki (Forster et al., 1994, cited by Jones et al., 2001). With Macrozamia lucida, the species has been the model for the work of Irene Terry, Robert B. Roemer and their colleagues on thermogenesis, the heat produced by the cones. For about two weeks, the cones produce a single heat peak every day around midday, which can reach 12 °C (21.6 °F) above the surrounding air (Roemer et al., 2008, 2012). This warming is driven by the cone’s respiration and goes with a surge of scent, more than 90 % of it β-myrcene (Terry et al., 2016).

In male cones, the heat follows the cone’s development: small late-afternoon rises while it is still growing, then large midday peaks, approaching 10 °C (18 °F) near the day of maximum pollen release, timed with the daily peak of air temperature; the authors suggest this helps drive the pollen-laden thrips out of the cone (Roemer et al., 2017). In 2008 the team found that the interval between peaks was not circadian; in 2022, experiments under constant temperature and darkness showed that the timing of the peaks is under the control of a circadian clock, influenced differently by cycles of ambient temperature and of light.

Conservation status and regulation

Macrozamia macleayi is listed as Least Concern (LC) on the IUCN Red List. The assessment, by J.D. Bösenberg, is dated 14 August 2020 and was published in 2022 (The World List of Cycads, GBIF and Crossref, checked on 26 October 2026). Jones et al. (2001) describe it as abundant and well conserved in Brisbane Forest Park, where it occurs in national parks and state forests, while the northern populations are well represented in state forests.

In Queensland it is listed as “Special least concern” under the Nature Conservation (Plants) Regulation, and WildNet treats it as a restricted plant; it is not listed under the federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC) (WildNet, checked on 26 October 2026).

Like other Macrozamia, it has been listed in CITES Appendix II since 4 February 1977, with annotation #4: seeds and pollen are exempt, but plants are not. In the European Union it falls under Annex B of Regulation (EC) No 338/97, as amended by Regulation (EU) 2026/1383, applicable since 29 June 2026 (Species+, checked on 26 October 2026). Check the regulations in force before any purchase or import, and buy only plants of proven cultivated origin.

Growing Macrozamia macleayi

No cultivation experience published under the name Macrozamia macleayi is known. Yet Miquel described it in 1868 from plants grown in Utrecht and by Van Houtte, which shows that it reached European collections in the nineteenth century. Its long confusion with Macrozamia miquelii suggests that some plants sold under that name may belong to it, but no source documents this. Its habitat points to an understorey plant, comfortable in light shade in free-draining soil, under a subtropical climate with summer rain. These are deductions from the wild, not tested advice.

Outdoor and in-ground cultivation

  • Light: in the wild, under open forest; dappled light or a bright position is a deduction from the habitat.
  • Soil: no published data; a free-draining soil suits Macrozamia in general.
  • Water: its region receives most of its rain in summer; water during growth and let the soil dry between waterings.
  • Space: an adult plant can carry leaves up to 2 m long.

Container cultivation

No container culture has been described. A deep pot suits the underground stem; in a pot the plant loses the protection that the soil gives the stem in winter (see Cold hardiness).

In cultivation in the UK, US and Australia

  • United States: San Diego Botanic Garden (Encinitas) and The Huntington (San Marino), both in California, declare the species to BGCI. A BGCI declaration says that a garden has held the plant, not that a living specimen is there today.
  • Australia: the System Garden of the University of Melbourne declares it to BGCI; neither the Royal Botanic Garden Sydney nor Mount Annan lists it in its online catalogue.
  • United Kingdom: no British garden declares it to BGCI (checked on 26 October 2026).

Montgomery Botanical Center, in Florida, lists no accession under this name in its online catalogue. No grower in the English-speaking world has published a cultivation result.

Propagation

Macrozamia macleayi is propagated by seed. A male and a female plant are needed, and outside Australia, without the thrips pollinator, the female cone must be hand-pollinated. Wear gloves to clean the seeds, whose flesh is toxic.

Pests and diseases

No pest or disease specific to Macrozamia macleayi is documented. For Macrozamia grown in Europe, growers’ forums mainly mention scale insects and rot in cold, wet soil (see the genus page).

Cold hardiness

The cold hardiness of Macrozamia macleayi is not documented: no cultivation result has been published under this name.

Mediterranean and European experience

No result has been published in Europe, in the ground or in a pot. Results published under the name Macrozamia miquelii cannot be transferred to it without a reliable identification.

United Kingdom, United States and Australia

No cold measurement exists. The species lives in subtropical south-eastern Queensland, between 100 and 500 m, and no weather station has been linked to its populations. In Britain and in the colder parts of the United States, a pot kept frost-free in winter is the prudent choice.

Toxicity and precautions

No toxicity data specific to Macrozamia macleayi have been published, but the risk is well documented for the genus. Macrozamia contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a poison of the liver; cattle that eat the leaves can develop a locomotor disorder of the hind legs (Healy, 1967), which McKenzie (2006) describes as irreversible, ending in paralysis of the hindquarters, with no treatment.

Treat the plant as toxic: wear gloves to handle the seeds and keep them out of reach of children and animals. In case of ingestion, contact a poison centre, a doctor or a vet without delay.

Traditional uses

No traditional use specific to Macrozamia macleayi is recorded. Other Macrozamia provided Aboriginal peoples with seeds that could be eaten after long processing (see the genus page); never eat cycad seeds.

Frequently asked questions

How does Macrozamia macleayi differ from Macrozamia miquelii?

Mainly by its leaves and female cones. Macrozamia macleayi has glossier, thinner-textured leaflets and narrower female cones (7 to 10 cm across, against 10 to 15 cm), and it grows further south, from Miriam Vale to Brisbane.

Why did the name macleayi disappear and come back?

Because it was sunk into synonymy in 1959. L.A.S. Johnson placed it under Macrozamia miquelii; Jones, Forster and Sharma reinstated it in 2001 after studying the group in the field.

Who was Macleay?

Probably William John Macleay (1820–1891), a naturalist and politician of New South Wales. Miquel thought he had discovered the plant near Moreton Bay.

Do its cones really heat up?

Yes. Published measurements show a daily heat peak of up to 12 °C (21.6 °F) above the surrounding air for about two weeks, linked to pollination by thrips.

Is it endangered?

No. The IUCN lists it as Least Concern (2022) and it remains common, notably in the Brisbane forests. Like all cycads, it is covered by CITES.

Is it poisonous?

Probably, like all cycads. No study deals with this species, but the seeds and leaves of Macrozamia are toxic to people and livestock.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Miquel, F.A.W. (1868). Nouveaux matériaux pour servir à la connaissance des Cycadées. Archives néerlandaises des sciences exactes et naturelles 3: 246–254. [Protologue of Macrozamia macleayi, pp. 250–251; facsimile read through The World List of Cycads.]
  • Jones, D.L., Forster, P.I. & Sharma, I.K. (2001). Revision of the Macrozamia miquelii (F.Muell.) A.DC. (Zamiaceae section Macrozamia) group. Austrobaileya 6(1): 67–94. [Reinstatement of the species, description, range, habitat, synonymy, etymology; full text.]
  • Forster, P.I. (1999). Typification and application of the name Macrozamia macleayi Miq. (Zamiaceae). Austrobaileya 5(3): 577. [Cited by Jones et al. (2001).]
  • Johnson, L.A.S. (1959). The families of cycads and the Zamiaceae of Australia. Proceedings of the Linnean Society of New South Wales 84: 64–117. [Synonymy under Macrozamia miquelii, according to Jones et al. (2001).]
  • Hill, K.D. (1998). Cycadophyta. In: McCarthy, P.M. (ed.), Flora of Australia 48: 597–661, 717–719. ABRS/CSIRO Publishing, Melbourne. [Treatment of these plants under Macrozamia miquelii, as stated in the online Flora of Australia.]
  • Forster, P.I., Machin, P., Mound, L. & Wilson, G. (1994). Insects associated with the reproductive structures of cycads in Queensland and north-east New South Wales, Australia. Biotropica 26: 217–222. [Thrips pollinator, according to Jones et al. (2001).]
  • Roemer, R.B., Terry, L.I. & Walter, G.H. (2008). Unstable, self-limiting thermochemical temperature oscillations in Macrozamia cycads. Plant, Cell & Environment 31(6): 769–782. doi:10.1111/j.1365-3040.2008.01795.x [Peer-reviewed paper; abstract read on PubMed.]
  • Roemer, R.B., Booth, D., Bhavsar, A.A., Walter, G.H. & Terry, L.I. (2012). Mathematical model of cycad cones’ thermogenic temperature responses: inverse calorimetry to estimate metabolic heating rates. Journal of Theoretical Biology 315: 87–96. doi:10.1016/j.jtbi.2012.09.003 [Peer-reviewed paper; abstract read on PubMed.]
  • Terry, L.I., Roemer, R.B., Booth, D.T., Moore, C.J. & Walter, G.H. (2016). Thermogenic respiratory processes drive the exponential increase of volatile organic compound emissions in Macrozamia cycad cones. Plant, Cell & Environment 39(7): 1588–1600. doi:10.1111/pce.12730 [Peer-reviewed paper; abstract read on PubMed.]
  • Roemer, R.B., Booth, D.T., Terry, L.I. & Walter, G.H. (2017). Thermogenesis and developmental progression of Macrozamia macleayi pollen cones. Australian Journal of Botany 65(5): 421–430. doi:10.1071/BT17048 [Peer-reviewed paper; abstract read through Crossref.]
  • Roemer, R.B., Terry, L.I., Booth, D.T. & Walter, G.H. (2022). Insights from an ancient gymnosperm lineage: ambient temperature and light and the timing of thermogenesis in cycad cones. American Journal of Botany 109(1): 151–165. doi:10.1002/ajb2.1810 [Peer-reviewed paper; abstract read on PubMed.]
  • Bösenberg, J.D. (2022). Macrozamia macleayi. The IUCN Red List of Threatened Species 2022: e.T178871A48868697. doi:10.2305/IUCN.UK.2022-1.RLTS.T178871A48868697.en [Least Concern; assessment dated 14 August 2020, from Crossref.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Etymology, as given by The World List of Cycads.]
  • Healy, P.J. (1967). Macrozamia poisoning. Institute of Inspectors of Stock of New South Wales Year Book. [Reprinted by Flock & Herd.]
  • McKenzie, R.A. (2006). Toxicology for Australian Veterinarians: cycads (Cycas, Macrozamia, Lepidozamia, Bowenia), pp. 282–288. Animal Health Australia, Australian Animal Pathology Standards Program (PDF): https://aapspextranet.animalhealthaustralia.com.au/wp-content/uploads/2019/04/tav7_17_unknowntoxins_pt2.pdf [Australian veterinary reference text; describes the cattle syndrome as irreversible, ending in paralysis of the hindquarters, with no treatment.]
  • 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 list.]