At 1,450 metres on Mount Kaputar, in the Nandewar Range of northwestern New South Wales, a cycad grows among snow gums. Snow falls four or five times a year. Frost is relentless. High winds rake the exposed ridgelines. And here, on north-facing basalt slopes in heath-like understorey and sub-alpine woodland, Macrozamia stenomera not only survives — it produces what has been called “perhaps the most intense blue foliage of any cycad”. But the colour is not even its most remarkable feature. The leaflets of Macrozamia stenomera are multi-divided — forked one to four times into progressively narrower segments, with up to 13 sub-leaflets per pinna — giving the fronds a plumose, conifer-like appearance unlike anything else in the genus. No other Macrozamia does this to the same degree. The plant looks more like a club moss or a juniper than a cycad. And then there is the ecological amplitude: this same species also grows on the hot, dry plains near Narrabri, at the foot of the ranges, in sandy soil under conditions that could hardly be more different from the sub-alpine summit. Few cycads span such a climatic gradient.
Described by L. A. S. Johnson in 1959, separated from the closely related Macrozamia heteromera, and named stenomera (Greek: “narrow parts”) for its divided, narrow-segmented leaflets, it belongs to the genus Macrozamia — the largest exclusively Australian cycad genus, with around 40 species — and within that genus it is one of the rarest, most visually distinctive, and potentially most cold-hardy species of all.
Quick Facts
| Scientific name | Macrozamia stenomera L.A.S.Johnson |
| Family | Zamiaceae |
| Origin | NW New South Wales (Nandewar Range / Mt Kaputar; disjunct at Moonbi Ranges near Tamworth) |
| Adult size | Acaulescent; caudex subterranean 8–15 cm diameter; 2–10 fronds, 40–80 cm long |
| Hardiness | −7 to −10 °C (19 to 14 °F) — potentially the most cold-hardy Macrozamia / USDA zones 8b–11 |
| IUCN | Vulnerable (VU) |
| CITES | Appendix II (all cycads) |
| Cultivation difficulty | 3/5 |
Taxonomy and Nomenclature
Macrozamia stenomera was described by L. A. S. Johnson in 1959 (Proceedings of the Linnean Society of New South Wales 84: 106), as part of the same landmark revision that created M. communis and resolved the M. spiralis confusion. Johnson found that M. stenomera, previously not distinguished from Macrozamia heteromera, warranted recognition as a separate species based on its much narrower, more profusely divided leaflets.
Etymology: from the Greek stenos (στενός), “narrow,” and meros (μέρος), “part” — referring to the narrow segments produced by the multiple divisions of the leaflets.
Section: Parazamia. A key botanical distinction: Macrozamia stenomera has hypostomatic leaflets (stomata on the lower surface only), whereas the related Macrozamia heteromera and Macrozamia glaucophylla both have amphistomatic leaflets (stomata on both surfaces). This character, combined with the much narrower, more profusely divided pinnae, cleanly separates the three species.
Synonyms: Macrozamia heteromera var. dicranophylloides J.Schust.; Macrozamia heteromera f. harmsii J.Schust.; Macrozamia heteromera var. tenuifolia C.Moore.
Affinities: related to Macrozamia glaucophylla (larger, also with divided pinnae, from the same region) and Macrozamia heteromera (pinnae divide once or twice, vs. the multiple divisions of M. stenomera). All three share the divided-pinnae character that is uncommon in the genus.
Common names: no established common name.
Morphological Description
Macrozamia stenomera is a small, dioecious, evergreen cycad of section Parazamia — and one of the most morphologically distinctive species in the genus.
Caudex: entirely subterranean, up to 20 cm long and 8–15 cm in diameter. Never forms an aerial trunk.
Leaves: 2–10 per crown, 40–80 cm long. The rachis is strongly twisted — up to 360°. The overall frond has a distinctive “plumose” or feathery appearance due to the multi-divided pinnae — unlike the flat, simple-pinnae look of most Macrozamia species, the fronds of M. stenomera recall the bushy texture of a conifer branch. Petiole 7–15 cm long. Up to 10 new fronds are produced per year.
The diagnostic character — multi-divided pinnae: 70–120 pinnae per leaf, each dichotomously divided 1–4 times into progressively narrower segments. Primary segments 2–4 mm wide; more divided segments 1–3 mm wide. The maximum observed number of sub-leaflets on a single pinna is 13. The multi-divisions give the fronds an extremely bushy appearance that makes it “virtually impossible to clearly distinguish the pinnae detail” without close-up examination (PACSOA). Towards the tip of the frond, the last few pinnae are usually entire (undivided). The bases of the pinnae are a distinctive burnt-yellow colour — more conspicuous than in most other Macrozamia species.
Colour forms: two basic varieties exist — one with green leaves and one with a blue-green cast. The blue form, grown in full sun, produces the most intense blue foliage of any cycad. In shadier conditions, the same plants appear limey green.
Cones:
- Male cones: small, with spined sporophylls.
- Female cones: small. Seeds 2–3.5 cm long.
Seeds: PACSOA describes the sarcotesta as an attractive lemon-yellow colour (sometimes with a green segment where the sporophylls have opened); NSW PlantNET records scarlet. This discrepancy may reflect population variation or maturation stage — the yellow seeds are one of the species’ most distinctive characters, unusual in a genus where red dominates.
Similar Species and Common Confusions
| Character | Macrozamia stenomera | Macrozamia heteromera | Macrozamia glaucophylla |
|---|---|---|---|
| Pinnae divisions | 1–4 times (up to 13 sub-leaflets) | 1–2 (–3) times | 1–2 times |
| Segment width | 1–3 mm (narrowest) | Broader | Broader |
| Stomata | Hypostomatic (lower only) | Amphistomatic (both) | Amphistomatic (both) |
| Frond appearance | Plumose / conifer-like | Less bushy | Less bushy, larger |
| Overall size | Small (40–80 cm fronds) | Medium | Larger |
| Seed colour | Lemon-yellow (or scarlet) | Red | Red |
The multi-divided, very narrow pinnae and the hypostomatic leaf surface are the two characters that definitively separate M. stenomera from its relatives. The plumose frond texture is visible in the field without magnification — the plant simply does not look like a typical cycad.
Distribution and Natural Habitat
Macrozamia stenomera is endemic to northwestern New South Wales, centred on the Nandewar Range, principally around Mount Kaputar (the highest point of the range, approximately 50 km east of Narrabri). A disjunct population occurs on the Moonbi Ranges near Tamworth. The species also grows on the plains near Narrabri in sandy soil — a remarkably different environment from the sub-alpine summit.
Ecological amplitude: the range of habitats occupied by M. stenomera is extraordinary for a cycad. At the high-altitude extreme, it grows on north-facing basalt slopes at ~1,450 m altitude on Mt Kaputar — among snow gums (Eucalyptus pauciflora), in heath-like understorey on exposed shallow soils and sub-alpine woodland on deeper soils. At the low-altitude extreme, it occurs on hot, dry sandy plains near Narrabri. The temperature differential between these habitats is enormous — up to 10 °C cooler at the summit than on the plains.
Climate at Mt Kaputar (upper altitudes):
| Parameter | Mt Kaputar (~1,450 m) |
|---|---|
| Frost | Frequent, severe |
| Snow | 4–5 times per year |
| High winds | Common on exposed ridges |
| Vegetation | Snow gums (E. pauciflora) above 1,350 m |
| Fire | Periodic bushfires, generally low intensity |
Climate at Narrabri (plains):
| Parameter | Narrabri (~210 m) |
|---|---|
| Mean annual temperature | 17–19 °C |
| Summer maximum | 33–36 °C (extreme >40 °C) |
| Winter minimum | 2–5 °C (frost regular) |
| Annual rainfall | 600–650 mm |
The species that grows in snow at 1,450 m also grows in 40 °C+ heat at 210 m. This ecological range is among the widest of any cycad.
Conservation
Macrozamia stenomera is listed as Vulnerable (VU). The restricted range (primarily Mt Kaputar and surrounds, plus a disjunct at Moonbi Ranges), small population size, and the species’ specific habitat requirements make it vulnerable to bushfire (even low-intensity fires can destroy cones and seedlings), habitat clearing, and potentially climate change (warming at high altitudes could shift the species’ niche). Mt Kaputar is protected within Mount Kaputar National Park.
Cultivation
| Hardiness | −7 to −10 °C (19 to 14 °F) — potentially the most cold-hardy Macrozamia / USDA zones 8b–11 |
| Light | Full sun to partial shade; full sun for best blue colour |
| Soil | Well-drained; tolerates sandy, loamy, and rocky substrates; tolerates limestone |
| Watering | Moderate; tolerates both wet and dry conditions |
| Adult size | Small: 40–80 cm fronds, compact rosette |
| Growth rate | Slow (up to 10 fronds/year) |
| Difficulty | 3/5 (mainly due to rarity of material) |
Macrozamia stenomera is easy to grow when material is available — which is the main difficulty. LLIFLE notes it is “easy to grow and suitable for well-drained sites in temperate or subtropical areas” and will “tolerate cool conditions in winter, as well as moderate frosts.” It does well in both wet and drought environments — consistent with its extraordinary ecological amplitude in the wild.
Cold hardiness — the headline: this is potentially the most cold-hardy Macrozamia species — growing at 1,450 m among snow gums, with snow 4–5 times per year, frequent severe frosts, and high winds. The subterranean caudex provides thermal insulation. USDA zone 8b is a realistic assessment for this species, making it the only Macrozamia for which we cautiously suggest zone 8b may be achievable in well-drained, slope-positioned sites where cold air drains away. For permanent outdoor planting, zone 9a is the safe minimum; zone 8b is for adventurous growers who understand the risks and are willing to accept potential losses in extreme years. In European Mediterranean climates, this species should be cultivable in open, exposed positions — not requiring the canopy protection needed by the subtropical species.
Light: full sun to partial shade. Full sun produces the most intense blue-green foliage — the character that makes this species legendary among cycad collectors. In shade, the colour fades to an ordinary limey green.
Soil: well-drained. The species grows on basalt, sandy soils, and rocky substrates in the wild. Tolerates limestone. Undemanding.
Watering: moderate. The species tolerates both wet conditions (the Mt Kaputar summit receives regular rain and mist) and dry conditions (the Narrabri plains). Not drought-adapted to the extent of M. macdonnellii, but not moisture-dependent either.
Container culture: excellent — the small size, compact habit, and distinctive plumose foliage make this a superb container specimen. Particularly recommended for growers who want to test cold tolerance by gradually exposing the plant to increasingly harsh conditions over successive winters.
Buying Advice
Availability: Macrozamia stenomera is very rare in cultivation and extremely difficult to obtain outside Australia. LLIFLE notes that “it is difficult to get plants out of Australia, and seed is hard to come by on this species.” Eudlo Cycad Gardens (Australia’s largest cycad nursery) lists it but describes it as “very rare in cultivation.” This scarcity, combined with its extraordinary aesthetics and cold hardiness, makes it one of the most desirable collector’s cycads in the genus. When material does become available, it commands premium prices.
Propagation
Seed: the only method. Clean the sarcotesta (gloves — toxic). Sow in well-drained mix at 25–30 °C. Germination is cryptocotylar. No pretreatment required. Growth is slow but steady (up to 10 fronds per year in established plants — faster than many Parazamia species).
Pests and Diseases
Scale insects: the most common pest. Manageable with horticultural oil.
Root rot: in waterlogged soils.
Toxicity: all parts are toxic (cycasin, macrozamin). The same warnings as for all Macrozamia species.
Landscape Use
Macrozamia stenomera is the collector’s holy grail among Macrozamia species — a plant that combines three characters found in no other species: the most intense blue foliage of any cycad, a unique plumose/conifer-like frond texture from the multi-divided pinnae, and extreme cold hardiness (snow gums as neighbours). For gardeners in cool, frost-prone climates who have been told that cycads are not for them, M. stenomera is the answer. Use it as a premium specimen in a rockery, in an alpine or sub-alpine garden (its natural habitat), or in a collection of rare Parazamia species where its extraordinary leaf form can be appreciated alongside the simple-pinnae species. The burnt-yellow callouses at the leaflet bases add a warm accent to the blue-grey foliage. The lemon-yellow seeds (when produced) are a striking departure from the red norm. For European growers in zones 9a–9b with well-drained sites, this species offers a combination of aesthetics and hardiness that no other cycad can match.
Frequently Asked Questions
Why is the foliage blue?
The blue-green colour is produced by a waxy bloom on the leaf surface — a trait enhanced by full sun exposure. In shade, the wax layer is thinner and the colour fades to green. The blue form of M. stenomera is described as having “perhaps the most intense blue foliage of any cycad.”
What are “multi-divided pinnae”?
Each leaflet (pinna) forks dichotomously — once, twice, three times, or up to four times — producing progressively narrower segments. A single pinna can have up to 13 sub-leaflets. This gives the frond a feathery, bushy, conifer-like texture unlike any other cycad.
Is it really the most cold-hardy Macrozamia?
Almost certainly. It grows at 1,450 m among snow gums, with snow 4–5 times per year and frequent severe frost. Only M. montana (which grows near Armidale at 980 m, with −9.3 °C minimum) comes close, but M. stenomera grows 470 m higher and in a harsher, more exposed environment. The subterranean caudex provides frost protection to the meristem.
Why is it so rare in cultivation?
The restricted wild range (primarily Mt Kaputar National Park), the small population size, the Vulnerable conservation status, and the difficulty of obtaining seed from protected wild populations all limit availability. Seeds rarely enter the international trade.
Authority Websites and Databases
POWO — Plants of the World Online (Kew)
https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:297209-1
Accepted species. First published in Proc. Linn. Soc. New South Wales 84: 106 (1959).
PACSOA — Palm and Cycad Societies of Australia
https://pacsoa.org.au/wiki/index.php/Macrozamia_stenomera
The most detailed account. Section Parazamia, subterranean caudex, unique multi-divided pinnae (up to 13 sub-leaflets). Distribution: Mt Kaputar (Nandewar Range), disjunct at Moonbi Ranges. Also on plains near Narrabri. Yellow seeds. Hypostomatic pinnae (vs. amphistomatic in M. heteromera and M. glaucophylla). Mt Kaputar at ~1,450 m with snow gums, snow, severe frosts. Related to M. glaucophylla and M. heteromera.
NSW PlantNET — Macrozamia stenomera
https://plantnet.rbgsyd.nsw.gov.au/cgi-bin…
Official NSW Flora: stem subterranean 8–15 cm diameter; leaves 2–10, 40–80 cm, rachis twisted to 360°; pinnae 70–120, 1–4 times dichotomously divided, primary segments 2–4 mm wide, divided segments 1–3 mm; seeds 2–3.5 cm, scarlet.
LLIFLE Encyclopedia
https://llifle.com/Encyclopedia/PALMS_AND_CYCADS/…
Comprehensive profile: unique plumose fronds with narrow-linear multi-divided pinnae. Two colour forms (green and blue-green). Mt Kaputar at 1,450 m — snow gums, snow 4–5×/year, severe frosts, high winds, low-intensity bushfires. Also on hot dry plains near Narrabri. Easy to grow but seed hard to obtain. Full sun for best blue colour.
Bibliography
Hill, K. D. (1998). Cycadophyta. Flora of Australia, 48, 597–661.
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.
Jones, D. L. (2002). Cycads of the World (2nd ed.). New Holland Publishers, Sydney.
Whitelock, L. M. (2002). The Cycads. Timber Press, Portland.