Macrozamia macdonnellii

Macrozamia macdonnellii is a trunked cycad with blue leaves from central Australia, the only cycad of the MacDonnell Ranges and the neighbouring ranges around Alice Springs, in the south of the Northern Territory. It belongs to the genus Macrozamia, all of whose other species live more than a thousand kilometres away, on the coasts and uplands of eastern and south-western Australia. First described in the genus Encephalartos, as Encephalartos macdonnellii, it stands out for its clear blue leaves and for its seeds, perhaps the largest of any cycad. Sought after by collectors, it remains rare and expensive in cultivation.

Key facts about Macrozamia macdonnellii

  • Accepted name: Macrozamia macdonnellii (F.Muell. ex Miq.) A.DC. (1868), published in de Candolle’s Prodromus 16(2): 537, accepted by The World List of Cycads; the Atlas of Living Australia gives the author as “(F.Muell. ex Miq.) F.Muell. ex A.DC.”
  • Former names and synonyms: Encephalartos macdonnellii F.Muell. ex Miq. (1863), the basionym
  • Family: Zamiaceae, order Cycadales
  • Common names: “MacDonnell Ranges Cycad” (Flora of Australia, Atlas of Living Australia)
  • Natural range: Australia, south of the Northern Territory: MacDonnell Ranges and associated ranges, including the George Gill Range and the Harts Range
  • IUCN status: Least Concern (LC), assessment by J.D. Bösenberg dated August 2020 and published in 2022
  • CITES and other protection: CITES Appendix II (annotation #4); Annex B in the European Union; Vulnerable under the Australian EPBC Act since 16 July 2000
  • Documented hardiness: one French report: young seedlings came through −3 °C (26.6 °F) for a few hours without damage in the Gard (post of 2018); no measured value for adult plants (see Cold hardiness)
  • Light and soil: in the wild, gullies, gorges and shaded slopes, on skeletal soils; in cultivation, full sun and a very mineral, very free-draining mix
  • Habit and adult size: trunk 0.4 to 3 m tall and 60 to 80 cm across; 50 to 120 blue leaves 1.5 to 2.2 m long (Flora of Australia)
  • In the UK, US and Australia: declared to BGCI by 27 institutions, among them Kew, Glasgow Botanic Gardens, Montgomery Botanical Center and Alice Springs Desert Park; three plants at Royal Botanic Gardens Victoria
  • Toxicity: no data specific to the species; seeds not eaten by Aboriginal people; toxic throughout the genus (see Toxicity and precautions)

How to recognise Macrozamia macdonnellii

It is a trunked Macrozamia whose leaves stay a deep blue, with very large seeds and female cones; in the wild, no other cycad grows anywhere near it. Unless stated otherwise, the measurements come from the Flora of Australia (Hill, 1998).

  • Trunk: aerial, 0.4 to 3 m tall and 60 to 80 cm across; the Palm and Cycad Societies of Australia (PACSOA) gives “to about 3 m”.
  • Leaves: 50 to 120 per crown, 150 to 220 cm long, moderately keeled, blue and dull, with 120 to 170 leaflets.
  • Petiole: 12 to 25 cm long and 15 to 25 mm wide at the lowest leaflet; the lower leaflets are reduced to spines.
  • Leaflets: simple, 20 to 30 cm long and 7 to 11 mm wide, the same colour or nearly so on both faces, with flat margins and a sharp tip.
  • Male cones: spindle-shaped, 25 to 40 cm long and 8 to 10 cm across.
  • Female cones: ovoid, 40 to 50 cm long and 20 to 27 cm across, the scales ending in a broad shield and a spine of 0 to 20 mm.
  • Seeds: ovoid, 60 to 80 mm long and 40 to 53 mm wide, with orange or orange-brown flesh; according to the Flora of Australia, they are “possibly the largest of all cycads”.

According to a French cycad specialist on the Fous de palmiers forum (2018), the species stays very blue even in a rainy climate and can hardly be confused except as a seedling, with Macrozamia fraseri or Macrozamia moorei; the adult is sturdier than Macrozamia moorei or Macrozamia johnsonii, with petioles broader at the base.

Hybrids

No hybrid is known. Separated by more than 1,400 km from any other species of the genus, the plant cannot hybridise in the wild, and no garden hybrid has been documented.

Possible confusion

In the wild no confusion is possible: it is the only cycad of central Australia. In cultivation, confusion comes mainly from labels.

  • Macrozamia moorei: in 2018, on the Fous de palmiers forum, a large plant grown in Thailand and presented as Macrozamia macdonnellii turned out to be a Macrozamia moorei, with much greener leaves. Macrozamia moorei has grey-green leaves and a taller trunk, and grows in Queensland.
  • Macrozamia fraseri: a Western Australian species with which young seedlings can be confused, according to the same specialist.

Taxonomy

Macrozamia macdonnellii is accepted by The World List of Cycads and the Australian Plant Census. Friedrich Anton Wilhelm Miquel published it in 1863, from a name by Ferdinand von Mueller, as Encephalartos macdonnellii F.Muell. ex Miq., in the Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen, Afd. Natuurkunde 15: 376; the type is kept at the National Herbarium of Victoria in Melbourne (MEL). In 1868, Alphonse de Candolle transferred it to the genus Macrozamia, in the Prodromus (16(2): 537).

This transfer followed the way genera were drawn in the nineteenth century: several Australian cycads described by Mueller in Encephalartos, an African genus, were moved to Macrozamia, the genus Miquel had created in 1842 for Australian species. For the reader, Encephalartos macdonnellii and Macrozamia macdonnellii therefore refer to the same plant; only the second name is in use.

The Flora of Australia links the species with the Macrozamia of Western Australia, through its well-defined petiole and its leaves bearing stomata on both faces. The genetic study by Ingham et al. (published online in 2012 in Diversity and Distributions), based on two regions of chloroplast DNA, reaches another conclusion: Macrozamia macdonnellii shares a haplotype with five eastern species and is therefore derived, fairly recently, from eastern Australian lineages, whereas the Western Australian species form a lineage isolated for a long time. The morphological and genetic views do not match.

Etymology and history

The epithet honours Sir Richard G. MacDonnell (1814–1881), governor of South Australia (Haynes, 2022, as given by The World List of Cycads). The ranges where the plant grows bear the same name.

According to Asmussen (2011), the explorer John McDouall Stuart and his party saw seeds of the species while crossing the MacDonnell Ranges in the early 1860s. Ingham et al. recall that it is often presented as an “ancient relict” of the humid forests that once covered the centre of the continent; their genetic data qualify that picture (see Taxonomy).

Common names

The Flora of Australia and the Atlas of Living Australia give “MacDonnell Ranges Cycad”. No Aboriginal name is attested in a reliable source, and no common name is attested in other languages.

In the wild

Macrozamia macdonnellii grows in the MacDonnell Ranges, in the south of the Northern Territory, and in associated ranges (Flora of Australia). The PACSOA cites the MacDonnell and Harts Ranges; other sources add the Krichauff and George Gill Ranges. The Flora of Australia describes it as very scattered on thin soils, on rocky slopes, in Triodia grassland or open woodland. Among the collections it cites are the Chewings Range, Mount Conway near Standley Chasm, Palm Valley and King Creek, in the George Gill Range.

The study by Preece, Duguid and Albrecht (2007), covering 143 sites in 13 localities, shows that the species occurs mainly where solar radiation is low (deep shade), where maximum temperatures are low, on steep slopes, in moist places close to drainage lines and on skeletal soils. Fire and rock cover predict its presence poorly; microclimate is the main limiting factor, which supports the idea of a climatic relict.

Pollination

Macrozamia macdonnellii is pollinated by a thrips of its own, Cycadothrips albrechti. Mound and Terry described this insect in 2001 in the International Journal of Plant Sciences, in a paper on the pollination of the species; it was described from individuals collected at Serpentine Gorge, where it breeds in the male cones (ThripsWiki). According to Brookes et al. (2015), the lineage of Cycadothrips albrechti split from that of Cycadothrips chadwicki, the thrips of the eastern Macrozamia, long before their present host plants appeared: the thrips has therefore changed host during its history.

Conservation status and regulation

Macrozamia macdonnellii is not threatened globally, but it is protected in Australia. The IUCN Red List classes it as Least Concern (LC), in the assessment by J.D. Bösenberg dated 21 August 2020 and published in 2022 (The World List of Cycads, GBIF and Crossref, checked on 26 October 2026); an earlier assessment, by K.D. Hill, was published in 2010.

In Australia, it has been listed as Vulnerable under the federal EPBC Act 1999 since 16 July 2000 (Flora of Australia; Atlas of Living Australia). Ingham et al. suggest that some isolated populations carrying unique haplotypes could be treated as separate conservation units.

For international trade, like other Macrozamia, it falls under CITES Appendix II, with annotation #4, which exempts seeds among other items (listing in force on 5 March 2026), and under Annex B in the European Union (Species+, checked on 26 October 2026). Plants sold must come from seed or legal cultivation; check the regulations in force before any purchase or import.

Growing Macrozamia macdonnellii

Macrozamia macdonnellii needs warmth, plenty of light and a very free-draining mix; excess water is the main danger. According to the PACSOA, it needs a hot, dry position in full sun, with excellent drainage.

Outdoor and in-ground cultivation

  • Light: full sun for an intense blue colour, according to growers. In the wild, however, the plant favours shaded slopes (Preece et al., 2007): light shade in the hottest hours remains an option in a very sunny climate.
  • Water: at the Jardin zoologique tropical in La Londe-les-Maures, in the Var (southern France), experience with the genus Macrozamia shows that watering once a week in summer, when there is no rain, is a minimum; for this species, let the soil dry out well between waterings. This Mediterranean experience, gained with other species of the genus, is useful for gardens with a similar climate, such as coastal California or southern Australia.
  • In the ground: a grower on the Côte Bleue, near Marseille (France), wrote in 2021 that the plant is “trouble-free in the ground”, provided it is watered in summer to get some growth. A plant grown in a pot since 2018 was planted out at Six-Fours-les-Plages (Var, France) in September 2021, with no reported outcome.
  • Growth: slow; on the Italian Tropicamente forum, a grower called it “exasperatingly slow” in 2011.

Container cultivation

  • Mix: very mineral. On the Fous de palmiers forum, a specialist nurseryman recommended in 2018 about 80% pumice and 20% coir, with a slow-release fertiliser; another grower, in the Var, moved to about 70% pumice.
  • Pot: deep, because the taproot, almost tuberous, is very brittle; growers on the forum use pots 24 to 30 cm tall and repot just after the leaves have flushed, from May to July.
  • Feeding: regular; without it, new leaves turn yellow, according to the same nurseryman.

In cultivation in the UK, US and Australia

  • Australia: Alice Springs Desert Park, the Australian Botanic Garden Mount Annan, the Australian National Botanic Gardens and the Botanic Garden of South Australia declare it to BGCI. The census of Royal Botanic Gardens Victoria, downloaded on 19 October 2026, records three plants of wild origin: two at Cranbourne (planted in 2015 and 2016) and one in the Grey Garden at Melbourne (2025). The species does not appear in the Garden Explorer of the Royal Botanic Garden Sydney.
  • United States: Montgomery Botanical Center (Coral Gables, Florida) holds three accessions in its online catalogue, and Fairchild Tropical Botanic Garden lists it in its Garden Explorer. Eleven other institutions declare it to BGCI, among them the Huntington, Lotusland, the Los Angeles County Arboretum, San Diego Botanic Garden, the Cal State Fullerton Arboretum, the University of California Botanical Garden at Berkeley, the New York Botanical Garden, Honolulu Botanical Gardens and the USDA National Plant Germplasm System.
  • United Kingdom: the Royal Botanic Gardens, Kew and Glasgow Botanic Gardens declare it to BGCI.

Twenty-seven institutions in all declare the species to BGCI (checked on 26 October 2026), the others in Egypt, Spain, France, Mexico, the Netherlands and New Zealand. A BGCI listing records a declaration by the garden, not necessarily a living plant on display today. No English-language grower’s report with a date, a place and a temperature has been found.

Propagation

Propagation is by seed only. A grower in Ravenna (Emilia-Romagna, Italy) reports on the Tropicamente forum that his three seeds, bought in 2013, germinated between a month later and July 2014, and that the first leaf appeared in March 2015. On the Fous de palmiers forum, the nurseryman already quoted advises leaving the seed attached while it feeds the seedling and handling the root with care when repotting. Clean the seeds wearing gloves.

Pests and diseases

No pest specific to the species is documented. The main risk in cultivation is root rot in a mix that stays too wet, as growers report.

Cold hardiness

The cold limit of Macrozamia macdonnellii is not known: the only report with a temperature concerns young seedlings at −3 °C (26.6 °F), and no garden or institution has published a measurement. No source gives a USDA zone for it.

Mediterranean and European experience

  • A grower in the Gard (France) reports on the Fous de palmiers forum, in a post of April 2018, that his Macrozamia macdonnellii, raised from seed sown in 2014 and with a caudex of about 6 cm, had already come through −3 °C (26.6 °F) for a few hours without damage to the foliage; he does not say when, nor whether they were in pots or in the ground. He thought they would stand more cold in a very free-draining soil with a quick rise in temperature during the day.

No other report is documented for the French Mediterranean coast or elsewhere in Europe. In 2014, the Australian nurseryman whose hardiness ranking of the Macrozamia was relayed on the same forum gave no opinion on this species. A grower at Six-Fours-les-Plages called it “the hardiest Macrozamia” in 2022, without supporting data.

United Kingdom, United States and Australia

No dated cultivation result with a temperature has been published. In the wild, the plants grow in sheltered gullies and on shaded slopes of an arid region, which says little about what they can withstand in the open.

Toxicity and precautions

It should be treated as toxic, even though no analysis specific to the species is documented. The Flora of Australia notes that the seeds were not eaten by Aboriginal people. Macrozamia contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a toxin of the liver, and their leaves cause nervous damage in cattle (Healy, 1967), irreversible according to McKenzie (2006). Keep the plant and its seeds out of reach of children, dogs and cats, wear gloves to clean seeds and, in case of ingestion, contact a poison centre, a doctor or a vet without delay.

Traditional uses

Unlike most Macrozamia, no account records an Aboriginal use of this species (Asmussen, 2011). According to Latz (1995, 1999), as cited by Asmussen, the seeds were not eaten because of the plant’s scarcity and restricted range, its abundant but infrequent seeding, and the lack of water, which made the long leaching needed to remove the toxins impossible.

Frequently asked questions

Where does Macrozamia macdonnellii grow?

In central Australia. It is the only cycad of the MacDonnell Ranges and the neighbouring ranges, around Alice Springs, in the Northern Territory. There it takes refuge in gullies, gorges and on shaded slopes.

Why are its leaves blue?

It is a character of the species. The Flora of Australia describes blue, dull leaves, and growers find that the colour persists even in a rainy climate. Full sun makes it more intense, according to them.

Is Macrozamia macdonnellii frost-hardy?

Nobody really knows. The only report concerns young seedlings at −3 °C (26.6 °F), undamaged. No data concern adult plants: in a pot, overwinter it frost-free and, above all, dry.

Does it really have the largest seeds of any cycad?

Possibly. The Flora of Australia gives seeds 6 to 8 cm long and calls them, cautiously, “possibly the largest of all cycads”.

Is the species endangered?

Not globally: the IUCN classes it as Least Concern (2022). It has nevertheless been listed as Vulnerable in Australia since 2000.

Why is it so expensive?

Because seed is scarce. According to a specialist nurseryman on the Fous de palmiers forum (2013), the populations are very isolated and hard to reach, and collecting permits are hard to obtain. Slow growth also raises the price of young plants.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Miquel, F.A.W. (1863). Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen, Afd. Natuurkunde 15: 376. [Publication of Encephalartos macdonnellii; reference from The World List of Cycads.]
  • de Candolle, A.L. (1868). Cycadaceae. Prodromus Systematis Naturalis Regni Vegetabilis 16(2): 522–548. [Transfer to Macrozamia, p. 537; reference from The World List of Cycads.]
  • Hill, K.D. (1998). Cycadophyta. In: McCarthy, P.M. (ed.), Flora of Australia 48: 597–661. CSIRO Publishing, Melbourne. [Reference treatment; online version.]
  • Mound, L.A. & Terry, I. (2001). Thrips pollination of the central Australian cycad, Macrozamia macdonnellii (Cycadales). International Journal of Plant Sciences 162(1): 147–154. doi:10.1086/317899 [Description of Cycadothrips albrechti; reference checked on Crossref and ThripsWiki.]
  • Preece, L.D., Duguid, A.W. & Albrecht, D.E. (2007). Environmental determinants of a restricted cycad in central Australia, Macrozamia macdonnellii. Australian Journal of Botany 55(6): 601–607. doi:10.1071/BT06122 [Abstract.]
  • Ingham, J.A., Forster, P.I., Crisp, M.D. & Cook, L.G. (2013). Ancient relicts or recent dispersal: how long have cycads been in central Australia? Diversity and Distributions 19(3): 307–316 (online 2012). doi:10.1111/j.1472-4642.2012.00936.x [Abstract.]
  • Brookes, D.R., Hereward, J.P., Terry, L.I. & Walter, G.H. (2015). Evolutionary dynamics of a cycad obligate pollination mutualism. Molecular Phylogenetics and Evolution 93: 83–93. doi:10.1016/j.ympev.2015.07.003 [Abstract.]
  • Asmussen, B. (2011). “There is likewise a nut…” A comparative ethnobotany of Aboriginal processing methods and consumption of Australian Bowenia, Cycas, Macrozamia and Lepidozamia species. Technical Reports of the Australian Museum, Online 23(10): 147–163. doi:10.3853/j.1835-4211.23.2011.1575 [Full text.]
  • Bösenberg, J.D. (2022). Macrozamia macdonnellii. The IUCN Red List of Threatened Species 2022: e.T42011A48868285. doi:10.2305/IUCN.UK.2022-1.RLTS.T42011A48868285.en [Least Concern; assessment dated 21 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. Flock & Herd. [Toxicity of the genus to livestock.]
  • 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.]