Stand in the understory of the Daintree Rainforest and look up: rising through the tangle of palms, ferns, and lianas, a single columnar trunk climbs 15, 18, sometimes over 20 metres toward the canopy, its surface sheathed in a dense armour of persistent leaf bases, its crown a magnificent rosette of dark green, arching fronds spreading six metres across. This is Lepidozamia hopei — Hope’s Cycad — the tallest living cycad on Earth. Where most cycads are squat, slow, understory shrubs measured in decades per metre of growth, Lepidozamia hopei is a cycad that has broken free of the understory and reached for the canopy, achieving heights that rival palms and exceed all other species in its ancient order. Endemic to the Wet Tropics of far north Queensland — a UNESCO World Heritage area of staggering biodiversity — this Lepidozamia specie is a living monument to the Gondwanan cycad flora of Australia, a lineage that has persisted in these rainforests since the continent was connected to Antarctica. Described in 1865 from a cultivated plant and named for Louis Hope, the father of the Queensland sugar industry, it remains one of the most spectacular cycads in the world and a powerful argument for why the ancient rainforests of northeastern Australia deserve every protection they can get.
Quick Facts
| Scientific name | Lepidozamia hopei (W.Hill) Regel |
| Family | Zamiaceae |
| Origin | Far north Queensland, Australia (Wet Tropics Bioregion) |
| Adult size | Trunk to 20 m tall, 50 cm diameter; crown spread to 6 m |
| Hardiness | −1 to −3 °C (30 to 27 °F) / USDA zones 10a–11 |
| IUCN | Least Concern (LC) |
| CITES | Appendix II (all cycads) |
| Cultivation difficulty | 2/5 |
Taxonomy and Nomenclature
Lepidozamia hopei was first described in 1865 as Catakidozamia hopei by the Scottish-Australian botanist Walter Hill, published in The Gardeners’ Chronicle and Agricultural Gazette (1865: 1107), based on a living plant grown by the German nursery firm Haage & Schmidt. In 1876, the German botanist Eduard August von Regel transferred the species to Lepidozamia in Gartenflora 25: 6. Interestingly, Johnson (1959) noted that Regel’s publication was not nomenclaturally based on Hill’s Catakidozamia hopei but on the horticultural name “Katakidozamia Hopei h. Haage et Schm.” — a garden name of no formal validity that had derived from Hill’s description through horticultural channels.
The specific epithet honours Louis Hope (1817–1894), of Cleveland, Queensland — known in Australia as the “father of the Queensland sugar industry” for establishing the first commercial sugar plantation in the colony. Hope was also an active and generous patron of horticulture, agriculture, and botany in Queensland. His name thus connects this cycad to the earliest era of European botanical exploration in tropical Queensland.
Synonyms: Catakidozamia hopei W.Hill (1865); Macrozamia hopei (W.Hill) W.Hill ex C.Moore (1884); Macrozamia denisonii var. hopei (W.Hill) J.Schust. (1932).
The genus name Lepidozamia derives from the Greek lepis (λεπίς), “scale,” referring to the scale-like structure of the persistent leaf bases that clothe the trunk — the most immediately visible character of the genus in the field.
Aboriginal names: Wunu, Julbin, Binggira, Miray, Ngarumba — reflecting the plant’s significance to Indigenous peoples of the Wet Tropics, who traditionally used the processed seeds as food.
Common names: Hope’s Cycad (English, the standard common name); Zamia Palm (an informal name used in Queensland, misleading as the plant is neither a Zamia nor a palm).
Morphological Description
Lepidozamia hopei is the tallest living cycad species on Earth. It is a large, palm-like, evergreen tree — the only cycad that routinely achieves the stature of a canopy or subcanopy tree.
Trunk: erect, cylindrical, usually single and unbranched, though forked trunks occur occasionally. The trunk reaches up to 20 m in height (the tallest measured specimen stands at 17.5 m, but trunks exceeding 20 m have been reported) and up to 50 cm in diameter. The surface is densely clothed in persistent, spirally arranged leaf bases — the “scales” that give the genus its name — creating a rough, armoured column. The bark exudate is very sticky. The internal stem structure shows alternating layers of bark and wood — a character unusual among cycads and visible in cross-section.
Leaves: forming a magnificent crown at the trunk apex. Each leaf is pinnate, 200–300 cm long, gracefully arching. A mature crown may carry numerous spreading fronds, creating a canopy spread of up to 6 m. Each leaf bears approximately 150–200 leaflets.
Leaflets: dark green, fairly stiff, leathery, 20–40 cm long and 1.5–3 cm wide, arising from the upper midline of the rachis — a diagnostic character of Lepidozamia (in most other zamiaceous genera, leaflets arise from the lateral edges of the rachis). The leaflets lack an obvious midrib; instead, 15–25 veins run parallel with the margins. Leaflet margins are entire. The leaflets are arranged in a distinctive V-shape along the rachis.
Cones: very large. Male cones are cylindrical, 25–40 cm tall and up to 14 cm in diameter. Female cones are ovoid, even larger — 40–60 cm tall (up to 80 cm according to some sources) and 20–30 cm in diameter. The Wet Tropics Management Authority reports cone lengths up to 70–80 cm. Sporophylls are non-peltate, shortly hairy on the outer surface, lacking spines or ornamentation. The species is dioecious.
Pollination: primarily by thrips (Thysanoptera), tiny insects attracted to the pollen of the male cones. Wind may play a minor secondary role. This is consistent with the insect-mediated pollination syndrome universal in cycads.
Seeds: large, 4–6.2 cm long and 2.5–3.5 cm wide, sheathed in a bright red sarcotesta when ripe — highly conspicuous against the dark green foliage. A female cone produces approximately 100 seeds. The red sarcotesta serves as an attractant for animal dispersers.
Seed dispersal: by Southern Cassowaries (Casuarius casuarius) and native rats. The cassowary — itself an iconic Wet Tropics species — swallows the seeds whole; the large, hard seed passes through the gut intact, germinating at a new site. This cycad–cassowary mutualism is one of the most emblematic ecological interactions in the Australian Wet Tropics.
Similar Species and Common Confusions
| Character | Lepidozamia hopei | Lepidozamia peroffskyana |
|---|---|---|
| Maximum height | 20 m (tallest cycad) | 7 m (occasionally more) |
| Trunk diameter | Up to 50 cm | Up to 50 cm or more |
| Cone size | Female to 60–80 cm | Female to 90 cm, up to 45 kg (among largest cycad cones) |
| Leaflet width | 1.5–3 cm | 2–4 cm (broader) |
| Habitat | Tropical rainforest | Subtropical/warm-temperate rainforest |
| Distribution | Far north QLD (Daintree–Tully) | SE QLD and NE NSW |
| Cold hardiness | −1 to −3 °C | −4 to −5 °C (hardier) |
The two species are geographically separated by over 1,000 km and do not co-occur. Lepidozamia hopei is the taller but more frost-tender species; Lepidozamia peroffskyana is shorter but hardier and produces the larger cones (among the heaviest of any cycad). In cultivation outside Australia, Lepidozamia peroffskyana is far more commonly grown due to its greater cold tolerance.
Distribution and Natural Habitat
Lepidozamia hopei is endemic to far north Queensland, from the Bloomfield River area in the north to the lowlands just south of Tully in the south. The core distribution lies within the Wet Tropics Bioregion, a UNESCO World Heritage area. The species occurs from near sea level to approximately 600 m elevation (some sources cite 1,000 m as the upper limit).
The habitat is tropical rainforest — primarily lowland and upland rainforest on protected slopes, along creek banks, and in sheltered positions within dense forest. It grows as a tall understory to subcanopy tree, towering over other understory vegetation but rarely reaching the forest canopy itself. The soils are well-structured loams, rich in organic matter, slightly acidic — typical of the deep, fertile rainforest floor of the Wet Tropics.
A notable specimen can be seen on the Blue Arrow track on Mt. Whitfield in Cairns — one of the most accessible places to encounter this species in the wild.
Climate in the native range:
| Parameter | Wet Tropics lowlands (Cairns–Tully) |
|---|---|
| Mean annual temperature | 24–26 °C |
| Mean winter minimum | 17–20 °C |
| Historical minimum | ~5 °C (light, short-lived frosts occasionally at higher elevations) |
| Mean summer maximum | 31–33 °C |
| Annual rainfall | 1,700–2,500 mm (summer-dominant monsoon) |
| Köppen classification | Af/Am (tropical rainforest / monsoon) |
This is a high-rainfall, warm, humid tropical climate with no dry season in the strictest sense — even the driest months receive substantial rainfall. The species is adapted to year-round moisture and warmth, explaining its limited cold tolerance.
Conservation
Lepidozamia hopei is assessed as Least Concern (LC) by the IUCN (2010 assessment) and as “Special Least Concern” (SL) under Queensland’s Nature Conservation Act. The species has several large and stable populations, and much of its habitat falls within the Wet Tropics World Heritage Area — one of the most rigorously protected conservation areas in Australia. The population trend is considered stable.
Despite this relatively secure status, potential threats include cyclone damage (the Wet Tropics are cyclone-prone, and the tall, slender trunk is vulnerable to wind), climate change (shifts in rainfall patterns or temperature could affect the species’ ecological niche), and localised habitat clearing at the periphery of its range. The cycad blue butterfly (Chilades pandava), an invasive pest from Southeast Asia that has spread through eastern Australia, is an increasing threat to all Australian cycads, including Lepidozamia hopei.
All cycads are listed on CITES Appendix II. The species is protected under Australian federal and Queensland state legislation.
Cultivation
| Hardiness | −1 to −3 °C (30 to 27 °F) / USDA zones 10a–11 |
| Light | Partial shade to deep shade (rainforest understory species) |
| Soil | Humus-rich, well-drained but moisture-retentive; slightly acidic |
| Watering | Regular, generous; keep moist year-round |
| Adult size | Potentially 15–20 m in ideal conditions; much smaller in cultivation outside the tropics |
| Growth rate | Moderate to fast in tropical conditions; very slow in temperate climates |
| Difficulty | 2/5 |
Lepidozamia hopei is surprisingly easy to grow given its imposing wild stature. Whitelock (2002) notes that “although this is a cycad of the wet Tropics, it also does well in warm temperate climates. In southern California, for example, the plant is routinely exposed to several degrees of frost each winter without experiencing leaf burn or other adverse effects.” However, the growth rate in temperate climates is dramatically slower than in the tropics.
Light: partial shade to deep shade. This is a rainforest understory/subcanopy species adapted to filtered light beneath a dense tropical canopy. It thrives in quite deep shade — an unusual capacity for such a large plant. In cultivation, provide dappled light or a position protected from hot afternoon sun. Young plants are particularly shade-tolerant.
Soil and drainage: humus-rich, well-drained but moisture-retentive. The rainforest-floor soil of the Wet Tropics is deep, organic-rich, and slightly acidic. In cultivation, a quality potting mix with composted bark, perlite, and coir replicates these conditions. Avoid heavy clay or alkaline substrates.
Watering: generous and regular. The native habitat receives 1,700–2,500 mm of rainfall annually, with no truly dry season. Keep the substrate consistently moist year-round. The species is sometimes found growing in creek beds in the wild, indicating tolerance of very high moisture levels. Less water is better than standing water, but more water is better than drought — this is not an arid-climate cycad.
Cold hardiness: moderate. The tropical lowland habitat suggests limited frost tolerance. However, Whitelock reports survival of several degrees of frost without damage in southern California, and Useful Tropical Plants notes that light, short-lived frosts occur occasionally within the native range (at higher elevations). Estimated tolerance: −1 to −3 °C for established plants. USDA zone 10a minimum. In cooler zones, grow as a container specimen and overwinter in a frost-free position.
Container culture: well suited when young. The plant sends out a large taproot and will eventually need a deep container. In tropical and subtropical climates, it grows well from seed and can be raised in containers for many years before in-ground planting. In temperate climates, container culture may be the only option — growth will be very slow but the plant will remain healthy given warmth and moisture.
Growth rate: in tropical conditions with ample heat and moisture, growth is moderate to fast by cycad standards — faster than most Cycas or Encephalartos species. In temperate conditions, growth slows dramatically.
Fertilization: regular applications of balanced slow-release fertilizer during the growing season. Responds well to organic mulch mimicking the rainforest-floor leaf litter layer.
Buying Advice
Availability: Lepidozamia hopei is available from specialist cycad and palm nurseries, particularly in Australia. It is less commonly offered outside Australia than its congener Lepidozamia peroffskyana, which is hardier and more widely cultivated. Seeds are occasionally available from specialist dealers.
Size expectations: do not expect a 20 m tree in your garden unless you live in the tropical lowlands of Queensland. In subtropical and warm-temperate climates, growth is very slow, and the plant will function as a medium-sized palm-like specimen for decades. The world-record heights are achieved only in the native rainforest over centuries.
Identification: in the nursery trade, distinguish from Lepidozamia peroffskyana by provenance (tropical QLD vs. subtropical QLD/NSW), slightly narrower leaflets, and the generally more tropical requirements. Young plants of both species look similar.
Propagation
Seed: the primary propagation method. Remove the red sarcotesta (gloves essential — the sarcotesta can irritate skin). Sow in a warm, moist, well-draining mix at 25–28 °C. Germination is cryptocotylar, expected in 8–16 weeks. Seedlings initially produce 8–14 linear leaflets per compound leaf. Seedling growth is moderate in warm conditions.
Offsets: the species does not readily offset. Seed is essentially the only propagation method.
Pests and Diseases
Cycad blue butterfly (Chilades pandava): an invasive pest from Southeast Asia that lays its eggs on new cycad fronds; the caterpillars devour the emerging soft tissue. An increasing threat to all Australian cycads, including Lepidozamia hopei. Control with Bacillus thuringiensis (Bt) or manual removal of eggs and larvae.
Scale insects and mealybugs: common in cultivation, particularly in less-than-ideal air circulation. Treat with horticultural oil or insecticidal soap.
Root rot: in waterlogged, poorly drained soil. Unlikely in the species’ preferred humus-rich, well-structured substrate, but possible if planted in heavy clay.
Toxicity: all parts are toxic (cycasin). The seeds were traditionally processed and consumed by Indigenous Australians through careful leaching of toxins — a deep cultural knowledge not to be replicated casually. Toxic to dogs, cats, livestock, and humans.
Landscape Use
Lepidozamia hopei is a prestige specimen plant for tropical and warm-subtropical gardens — a cycad that grows to the scale of a palm, with the deep-time botanical credentials of a 200-million-year-old lineage. In tropical Queensland, it is the ultimate understory tree: plant it beneath tall palms or rainforest trees, along shaded watercourses, or as a dramatic avenue in a large garden. The combination of the tall, scaled trunk, the arching 3 m fronds, and the massive bright-red-seeded cones creates a visual impact unmatched by any other cycad. In subtropical and warm-temperate gardens (zone 10a+), it functions as a slow-growing but supremely elegant specimen, eventually reaching palm-like proportions. It pairs beautifully with other Wet Tropics plants: Licuala ramsayi (fan palm), Archontophoenix alexandrae (Alexandra palm), Bowenia spectabilis, tree ferns, and gingers. For gardens with space and ambition, this is the cycad that comes closest to recreating the experience of walking through a Cretaceous forest.
Frequently Asked Questions
Is Lepidozamia hopei really the tallest cycad?
Yes. With trunks reaching 20 m and the tallest measured specimen at 17.5 m, it holds the record for the tallest living cycad. The only cycad that rivals it in overall mass is Encephalartos laurentianus from Central Africa, which can reach 100 cm in trunk diameter but only 15 m in height (and is often decumbent).
How fast does Lepidozamia hopei grow?
In its native tropical rainforest, growth is moderate to fast by cycad standards — faster than most genera. In temperate climates, growth is very slow. A plant in southern California may take decades to develop a visible trunk, while one in tropical Queensland can achieve several metres in the same time given adequate heat and moisture.
Can I grow Lepidozamia hopei outside the tropics?
Yes. Whitelock reports that plants in southern California survive several degrees of frost without leaf damage. However, growth will be dramatically slower than in the tropics. In cool climates, treat it as a long-term container specimen, providing warmth, shade, and moisture during the growing season and frost-free conditions in winter.
What disperses the seeds?
The bright red sarcotesta attracts Southern Cassowaries and native rats, which consume the fleshy seed coat and disperse the large, hard seeds. The cycad–cassowary mutualism is one of the most iconic ecological interactions in the Australian Wet Tropics.
Is Lepidozamia hopei toxic?
Yes. Like all cycads, all parts contain cycasin and other toxic glycosides. The seeds were traditionally processed and consumed by Indigenous Australians after careful detoxification, but the raw plant is poisonous. Toxic to dogs, cats, livestock, and humans.
Authority Websites and Databases
POWO — Plants of the World Online (Kew)
https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:297149-1
The accepted nomenclatural record. Full synonymy: Catakidozamia hopei (1865), Macrozamia hopei (1884), Macrozamia denisonii var. hopei (1932).
World List of Cycads — cycadlist.org
https://cycadlist.org/scientific_name/371
Nomenclatural record: first published in Gartenflora 25: 6 (1876). Etymology (Haynes 2022): honouring Louis Hope (1817–1894), patron of horticulture in Queensland. Nomenclatural note from Johnson (1959) on the relationship between Regel’s publication and Hill’s Catakidozamia. Aboriginal names: Wunu, Julbin, Binggira, Miray, Ngarumba.
Lucid Rainforest Key — Lepidozamia hopei
https://apps.lucidcentral.org/rainforest/text/entities/lepidozamia_hopei.htm
Detailed morphological description (Flora of Australia standard): single-stemmed palm-like tree, ~150+ leaflets per leaf, leaflet blades 20–40 × 1.5–3 cm, 15–25 parallel veins, male cones 25–30 × 20 cm, female cones 40–60+ × 20–30 cm, seeds 4–6.2 × 2.5–3.5 cm with bright red sarcotesta. Fruit eaten by cassowaries and native rats.
Wet Tropics Management Authority — Cycads
https://www.wettropics.gov.au/cycads
Notes the species as “the world’s tallest cycad, having been recorded at up to 20 m.” Reports cone lengths up to 70–80 cm. Mentions the accessible specimen on Mt. Whitfield in Cairns.
Useful Tropical Plants — Lepidozamia hopei
https://tropical.theferns.info/viewtropical.php?id=Lepidozamia+hopei
Whitelock-sourced data: native climate temperatures 5–33 °C, rainfall 1,700–2,500 mm. Cultivation notes: grows well from seed, rapidly with heat and moisture, survives frost in southern California, very slow in temperate climates. Traditional food of Aboriginal peoples.
Britannica — Lepidozamia
https://www.britannica.com/plant/Lepidozamia
Genus overview: two species, trunk clothed in persistent leaf bases, rachis thickened on underside. L. hopei is the tallest extant cycad (17+ m).
PACSOA — Palm and Cycad Societies of Australia
https://www.pacsoa.org.au/wiki/Lepidozamia
Genus and species cultivation information for the Australian context.
C4 — Community for Coastal and Cassowary Conservation
https://cassowaryconservation.org/plants/lepidozamia-hopei-hopes-cycad/
Notes the species as cassowary food. Female cones produce ~100 seeds, 40–62 mm × 25–40 mm.
Bibliography
Cooper, W., & Cooper, W. T. (1994). Fruits of the Rain Forest: A Guide to Fruits in Australian Tropical Rain Forests. GEO Productions, Cairns.
Hill, K. D. (1998). Lepidozamia. In P. M. McCarthy (Ed.), Flora of Australia, 48, 639–641.
Hill, W. (1865). Catakidozamia hopei. The Gardeners’ Chronicle and Agricultural Gazette, 1865, 1107.
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.
Norstog, K. J., & Nicholls, T. J. (1997). The Biology of the Cycads. Cornell University Press, Ithaca.
Regel, E. A. von (1876). Lepidozamia hopei. Gartenflora, 25, 5–6.
Whitelock, L. M. (2002). The Cycads. Timber Press, Portland.