Ceratozamia oliversacksii is a cycad of southern Oaxaca, in Mexico, that grows in the cloud forests of the eastern Sierra Madre del Sur, on humus-covered limestone rocks between 1,040 and 1,850 m (about 3,410 to 6,070 ft). Described in 2022, this species of the genus Ceratozamia is named after the neurologist and writer Oliver Sacks, a lover of cycads and of Oaxaca. A large plant with drooping leaves that are green from the moment they emerge, it has not yet been assessed by the IUCN.
Key facts about Ceratozamia oliversacksii
- Accepted name: Ceratozamia oliversacksii D.W.Stev., Mart.-Domínguez & Nic.-Mor. (2022), accepted by The World List of Cycads (version 2026.08.15), by the 2022 monograph of the genus and by the World Checklist of Vascular Plants (WCVP, the database behind POWO, read via GBIF)
- Former names and synonyms: none
- Family: Zamiaceae, order Cycadales
- Common names: none recorded
- Natural range: Mexico, southern Oaxaca (Sierra Madre del Sur: municipalities of Candelaria Loxicha, San Agustín Loxicha, Santa Catarina Juquila and San Miguel del Puerto), 1,040 to 1,850 m
- IUCN status: Not Evaluated; Vulnerable proposed as a preliminary category by its authors
- CITES and other protection: CITES Appendix I (whole genus, since 1985); Annex A in the European Union, seeds included
- Documented hardiness: no data (see Cold hardiness)
- Light and soil: in the wild, karst rocks rich in organic matter, in cloud forest and at its transition with pine forest; no published growing advice
- Habit and adult size: trunk lying on the ground, 30 to 80 cm long; 7 to 36 leaves (up to 50), 1.2 to 2.6 m long
- In the UK, US and Australia: no garden declares it to BGCI PlantSearch (see In cultivation)
- Toxicity: no data for the species; treat it as poisonous (see Toxicity and precautions)
How to recognise Ceratozamia oliversacksii
According to the 2022 monograph, Ceratozamia oliversacksii is characterised by leaves that are green as soon as they emerge and by leaflets that are both linear and papery. In the key to the genus, its long, slender petiole prickles, at least 5 mm long, and the thin horns of its male cone scales set it apart from similar species. The monograph describes it as follows:
- Trunk: above ground, lying on the ground, 30 to 80 cm long and 10 to 40 cm in diameter; persistent, triangular, reddish-brown cataphylls, with brown wool when they emerge.
- Leaves: 7 to 36 (up to 50), drooping, 124 to 258 cm long; green with brown hairs when they emerge, then hairless. The petiole, 45 to 110 cm long, green then dark green, carries 40 to 65 thin prickles 5 to 7 mm long; the axis, 85 to 182 cm long, is prickly.
- Leaflets: 24 to 47 pairs, linear, flat or arching, papery, green and hairless, with a drawn-out, usually symmetrical tip; the middle ones measure 25 to 40 cm by 2.3 to 3.6 cm.
- Male cones: single, cylindrical, upright, 20 to 35 cm long and 3 to 5.7 cm across, greenish with reddish hairs, then greenish yellow; stalk 10 to 15 cm long.
- Female cones: single, cylindrical, upright, 33 to 36 cm long and 11.5 to 14 cm across, greenish yellow when they emerge, then green, hairless or with reddish-brown hairs, with an acute tip; stalk 8 to 10 cm long. They carry 80 to 210 scales, in 9 or 10 vertical rows of 11 to 13, with straight horns 3 to 5 mm long.
- Seeds: oval, 2.45 to 2.65 cm long, with whitish-yellow to yellow flesh before ripening, light brown when ripe.
Hybrids
No natural or garden hybrid has been documented.
Possible confusion
The 2022 monograph compares it with three other large Ceratozamia of southern Mexico:
- Ceratozamia leptoceras, of the Sierra Madre del Sur in Guerrero: linear but membrane-thin leaflets; its male cone scales have a long, linear sterile tip, and the base of its female cone scales is densely hairy.
- Ceratozamia robusta, of Chiapas and Guatemala: dark brown young leaves, lance-shaped leaflets and larger cones (male cone up to 70 cm long).
- Ceratozamia subroseophylla, of southern Veracruz (the 2022 monograph also included plants from Tabasco, assigned to Ceratozamia gigantea since 2024): greenish-brown petiole and axis covered in abundant, stout prickles, and lance-shaped leaflets.
Origin helps a great deal: Ceratozamia oliversacksii is the only one of these species known from southern Oaxaca.
Taxonomy
Ceratozamia oliversacksii is accepted by The World List of Cycads, by the 2022 monograph and by the WCVP, the database behind POWO (read via GBIF on 30 October 2026), which places it in south-western Mexico. It was described in 2022 by L. Martínez-Domínguez, F. Nicolalde-Morejón, F. Vergara-Silva and D.W. Stevenson in the Kew Bulletin (77: 211–219), in an article entitled “Ceratozamia oliversacksii (Zamiaceae), a new species of gymnosperm from western Oaxaca, Mexico”, published online in February 2022. The name itself is attributed to Stevenson, Martínez-Domínguez and Nicolalde-Morejón. The account given here follows the 2022 monograph of the genus, by the same team, which takes up its data.
The holotype is a female plant collected on 10 June 2021 in the municipality of Candelaria Loxicha, at 1,616 m, by Martínez-Domínguez, Nicolalde-Morejón and M. Rios-Méndez (no. 2261). It is held in the CIB herbarium of the Universidad Veracruzana, with isotypes at Kew (K), Mexico City (MEXU) and New York (NY).
The species had been collected long before it was named: the 2022 monograph cites specimens gathered in 1965 by J. Rzedowski and R. McVaugh in the municipality of Santa Catarina Juquila, then collections from 2000 to 2005. No published source says under which name these plants were filed before 2022. The species was not included in the 2023 phylogeny of the genus by Habib and colleagues, so its relationships have not been tested with DNA.
Etymology and history
The epithet honours Oliver Sacks (1933–2015), the neurologist and historian of science, who loved cycads: he wrote about them in The Island of the Colorblind and Cycad Island (1997) and described his attachment to Oaxaca in Oaxaca Journal (2002). The tribute thus brings together his two passions, cycads and Oaxaca (The World List of Cycads, after Haynes 2022; 2022 monograph).
No source documents its introduction into cultivation.
Common names
No common name is recorded in English or in any other language: the 2022 monograph records none.
In the wild
According to the 2022 monograph, Ceratozamia oliversacksii grows along the eastern Sierra Madre del Sur, in the Oaxacan highlands, on karst rocks rich in organic matter, in cloud forest and in the transition zone between cloud forest and pine forest, between 1,040 and 1,850 m. The specimens examined come from the municipalities of Candelaria Loxicha, San Agustín Loxicha, Santa Catarina Juquila and San Miguel del Puerto.
The authors visited four populations, each of 50 to 300 adult plants, with every age class present, from seedlings to plants bearing cones. No study of its pollination or cone calendar has been published.
Conservation status and regulation
Ceratozamia oliversacksii has not been assessed on the IUCN Red List (The World List of Cycads, version 2026.08.15; the Red List data distributed through GBIF give no category, checked on 30 October 2026). Its authors propose, as a preliminary assessment, the category Vulnerable, based on the four populations visited and on the presence of all age classes. This proposal has no official standing.
Like the whole genus, it has been covered by CITES Appendix I since 1 August 1985 (the genus had been in Appendix II since 1977), and by Annex A of Regulation (EC) No 338/97 in the European Union (annexes now set by Regulation (EU) 2026/1383, applicable since 29 June 2026), seeds included. Species+ does not yet list the species under its own name, but the listing covers the whole genus (“Ceratozamia spp.”) and therefore applies to it (checked on 30 October 2026). International trade in wild-collected plants for commercial purposes is banned; only artificially propagated plants with the required permits can be traded.
This general information does not replace the official texts: check the regulations in force before buying, importing or exchanging plants, and ask for proof of origin.
Growing Ceratozamia oliversacksii
No growing advice specific to Ceratozamia oliversacksii has been published, no grower has reported on it, and no public collection declares it.
Its habitat, humus-covered limestone rocks in cloud forest, points to partial shade, regular moisture and a free-draining mix rich in organic matter. Its size, with leaves of more than 2 m, suits it to planting in the ground or to a very large container. These pointers are drawn from the habitat and the description and have not been confirmed by published trials.
Outdoor and in-ground cultivation
No outdoor planting has been documented. In its cloud forest, it grows in shade and constant humidity; any trial outdoors would be limited to frost-free, humid climates.
Container cultivation
No container-grown plant has been documented. A young plant would need a deep pot and a mineral, free-draining mix with organic matter; the long leaves of adults quickly outgrow a container.
In cultivation in the UK, US and Australia
No garden declares Ceratozamia oliversacksii to BGCI PlantSearch (queried on 30 October 2026), and the online catalogue of Montgomery Botanical Center (Coral Gables, Florida) has no accession under this name. No British, American or Australian collection is documented.
Propagation
No data exist for the species. Like all Ceratozamia, it has separate male and female plants; it is propagated from fresh seed after pollination, by hand in cultivation. Handle seeds wearing gloves.
Pests and diseases
No pest or disease specific to the species has been documented. The usual risks for Ceratozamia in cultivation are rot in cold, sodden soil and scale insects.
Cold hardiness
No cold-hardiness data exist for Ceratozamia oliversacksii, described in 2022 and not yet in cultivation as far as sources show.
Mediterranean and European experience
No cultivation result has been published in Europe. The Jardin zoologique tropical in La Londe-les-Maures (Var, on the French Riviera) has published no observation of this species. Until trials exist, keep it frost-free.
United Kingdom, United States and Australia
No dated cold record and no commercial hardiness rating have been published. In the UK it would be a plant for a heated glasshouse.
Toxicity and precautions
No toxicity study specific to Ceratozamia oliversacksii has been published. The risk is well documented in other cycads: their tissues, and above all their seeds, contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a compound harmful to the liver and nervous system. Dogs, livestock and people can be seriously poisoned. In the absence of evidence to the contrary, treat the plant as poisonous: keep seeds and leaves out of reach of children and animals, wear gloves to clean seeds, and if any part is swallowed, call a poison centre, a doctor or a vet straight away.
Traditional uses
The 2022 monograph records no use for this species.
Frequently asked questions
Why is it named after Oliver Sacks?
To honour the neurologist and writer Oliver Sacks (1933–2015). He loved cycads, which he wrote about in The Island of the Colorblind and Cycad Island, and described his attachment to Oaxaca in Oaxaca Journal.
Where does it grow?
In southern Oaxaca, Mexico. It lives in the cloud forests of the Sierra Madre del Sur, between 1,040 and 1,850 m.
How can I recognise Ceratozamia oliversacksii?
By its leaves, green as soon as they emerge, and its linear, papery leaflets. The petiole carries long, slender prickles, and the female cone, with an acute tip, has 11 to 13 scales per vertical row.
How does it differ from Ceratozamia leptoceras?
Mainly by its leaflets and cones. Ceratozamia leptoceras, of Guerrero, has membrane-thin leaflets, male cone scales with a long, linear sterile tip and female cone scales with a hairy base.
Is it endangered?
It has not been officially assessed. The IUCN has not evaluated it; its authors propose Vulnerable, with four known populations of 50 to 300 adults.
Can I grow one?
In principle, yes, but no collection is known to hold it. The whole genus is in CITES Appendix I: only cultivated plants with their paperwork may be traded.
Can it take frost?
Nobody knows. No trial has been published; keep it frost-free.
Further reading on Succulentes
- How to Grow Cycads from Seed: Germination, Seedling Care and Propagation Setup
- Watering Cycads: Common Mistakes and How to Avoid Them
- Is Sago Palm Toxic to Dogs, Cats & Children? What to Know
Sources
Reference sites
- The World List of Cycads (version 2026.08.15), Ceratozamia oliversacksii: https://cycadlist.org/scientific_name/910 — authors, publication, type, range, IUCN status (Not Evaluated), etymology. Checklist of the IUCN Cycad Specialist Group, reliable; reread on 30 October 2026.
- World Checklist of Vascular Plants (WCVP, Royal Botanic Gardens, Kew), via GBIF, Ceratozamia oliversacksii: https://api.gbif.org/v1/species/213762090 — accepted name, place of publication (Kew Bull. 77: 212, 2022), south-western Mexico. Kew data, the basis of POWO, distributed by GBIF; consulted on 30 October 2026.
- PubMed Central, monograph of Ceratozamia (PhytoKeys 208): https://pmc.ncbi.nlm.nih.gov/articles/PMC9849018/ — description, type, range, altitude, habitat, preliminary status, key, comparison with Ceratozamia leptoceras, Ceratozamia robusta and Ceratozamia subroseophylla. Peer-reviewed article, open access.
- Species+ (UNEP-WCMC), Ceratozamia: https://speciesplus.net/species#/taxon_concepts/13147/legal — CITES Appendix I since 1 August 1985, Annex A in the European Union; the species is not listed under its own name. Official CITES and EU database; checked on 30 October 2026.
- BGCI PlantSearch: https://plantsearch.bgci.org/ — no garden declaring the species. Global database of garden lists; queried on 30 October 2026.
- Montgomery Botanical Center, living collection: https://www.montgomerybotanical.org/research/living-collection/ — no accession of the species in its BG-BASE catalogue. Specialist cycad garden; catalogue queried on 30 October 2026.
Bibliography
- Martínez-Domínguez, L., Nicolalde-Morejón, F., Vergara-Silva, F. & Stevenson, D.W. (2022). Ceratozamia oliversacksii (Zamiaceae), a new species of gymnosperm from western Oaxaca, Mexico. Kew Bulletin 77: 211–219. https://doi.org/10.1007/s12225-021-09992-x [Original description; its data are taken up in the 2022 monograph.]
- Martínez-Domínguez, L., Nicolalde-Morejón, F., Vergara-Silva, F. & Stevenson, D.W. (2022). Monograph of Ceratozamia (Zamiaceae, Cycadales): an endangered genus. PhytoKeys 208: 1–102. https://doi.org/10.3897/phytokeys.208.80382 [Description, range, preliminary status, key; open access.]
- Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. https://doi.org/10.11646/phytotaxa.550.1.1 [Source of the etymology given by The World List of Cycads.]
- Calonje, M., Stevenson, D.W. & Osborne, R. (2026). The World List of Cycads, version 2026.08.15. Montgomery Botanical Center, Coral Gables. https://doi.org/10.5281/zenodo.21958524 [Reference checklist.]