Ceratozamia mixeorum

Ceratozamia mixeorum is a cycad of north-eastern Oaxaca, in southern Mexico, that grows in the cloud forests and oak forests of the Sierra Mixe, on limestone rocks between 1,170 and 2,150 m (about 3,840 to 7,050 ft): it is one of the highest-growing species of the genus Ceratozamia. Described in 1997 and named after the Mixe people, it is easily recognised by its cones, held on remarkably long stalks, the female cone hanging down when ripe. Local children play with its male cones, which they call “carrete”. The IUCN assesses it as Endangered.

Key facts about Ceratozamia mixeorum

• Accepted name: Ceratozamia mixeorum Chemnick, T.J.Greg. & Salas-Mor. (issue dated 1997, published in 1998), accepted by The World List of Cycads (version 2026.08.15), by the 2022 monograph of the genus, by Species+ 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: no English name; in Oaxaca, “carrete” (Spanish, “ox cart”)
• Natural range: Mexico, north-eastern Oaxaca (southern Sierra Norte, Mixe highlands), 1,170 to 2,150 m
• IUCN status: Endangered (EN A2acd+4acd; B1ab(i,ii,iii,iv,v)), assessment published in 2022
• 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, steep, heavily shaded slopes in cloud forest, on a crumbly, stony clay of pH 5 according to the original description, and on karst rocks according to the 2022 monograph; no published growing advice
• Habit and adult size: trunk 30 cm to 1.25 m long, sometimes forked; 3 to 17 leaves (up to 30), 0.85 to 2.5 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 mixeorum

Its most striking feature is the length of its cone stalks: the female cone hangs on a stalk 12 to 23.5 cm long, and the male cone stands on a stalk 10 to 15 cm long, far longer than in most species of the genus. Its large, drooping leaves have a petiole bristling with 30 to 50 slender prickles. The 2022 monograph describes it as follows:

• Trunk: above ground, lying on the ground, 30 to 100 cm long and 18 to 25 cm in diameter; persistent, triangular, reddish-brown cataphylls, densely woolly when they emerge.
• Leaves: 3 to 17 (up to 30), drooping, 85 to 246 cm long; light green and glaucous with light-brown hairs when they emerge, then hairless. The petiole, 46 to 132 cm long, carries 30 to 50 thin prickles 2 to 4 mm long; the axis carries only a few.
• Leaflets: 19 to 35 pairs, lance-shaped, usually curved, papery, green and hairless; the middle ones measure 24 to 39 cm by 1.9 to 2.9 cm.
• Male cones: usually single, cylindrical, upright, 22 to 30 cm long and 4.5 to 7 cm across, greenish with reddish hairs, then greenish yellow; stalk 10 to 15 cm long.
• Female cones: single, cylindrical, 23 to 32 cm long and 12 to 16 cm across, green with brown to blackish hairs when ripe; hanging stalk 12 to 23.5 cm long. The 60 to 112 scales, in 6 to 9 vertical rows, carry two straight horns about 1 cm long.
• Seeds: oval, 2.2 to 3 cm long, with whitish-yellow to yellow flesh before ripening, light brown when ripe.

The original description (Chemnick, Gregory and Salas-Morales, 1997) adds several details. The trunk, 34 to 125 cm long, is half buried, and a fifth to a quarter of adult plants are forked, some with up to four branches. The leaves, 1.46 to 1.98 m long, come in flushes of 5 to 11; new leaves are a bright pea green, turning dark green with age, and adult plants can carry up to three crowns. The leaflets, 49 to 77 in all, are described as moderately leathery rather than papery. The female cone is held horizontally when receptive and hangs down when ripe. From a distance, developing cones of both sexes look orange, because of the dark red down covering their light yellow scales.

Hybrids

No natural or garden hybrid has been documented.

Possible confusion

• Ceratozamia whitelockiana, of the Sierra Norte of Oaxaca: almost identical foliage. According to the 2022 monograph, it has few prickles on the petiole (3 to 22, against more than 28) and none on the axis, a female cone on a short stalk (1 to 4 cm), and fewer scales (4 or 5 vertical rows of 5 to 8 scales, against 6 to 9 rows of 10 to 14).
• Ceratozamia matudae, of Chiapas: also has pendent female cones on long stalks, but, according to the original description of Ceratozamia mixeorum, much shorter leaves, narrower leaflets and much smaller cones.
• Ceratozamia zaragozae, of San Luis Potosí: a small female cone hanging on a long stalk, but small, spirally arranged, unarmed leaves, in a much drier habitat far to the north (original description).

With cones, the long stalks separate Ceratozamia mixeorum at once. Without cones, the number of prickles on the petiole and axis is the best clue against Ceratozamia whitelockiana.

Taxonomy

Ceratozamia mixeorum is accepted by The World List of Cycads, by the 2022 monograph, by Species+ 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 by Jeffrey Chemnick, Timothy J. Gregory and S. Salas-Morales in Phytologia (83(1): 47–52), in an article entitled “Ceratozamia mixeorum (Zamiaceae), a new species from Oaxaca, Mexico with comments on distribution, habitat, and species relationships”. The issue is dated July 1997; The World List of Cycads and the 2022 monograph state that it was actually published in 1998, while the WCVP keeps 1997.

Type

The type was collected near Juquila Mixes in May 1997 by Chemnick and Gregory (no. 49). The original description named the herbarium of the Huntington (HNT) for the holotype, with duplicates to be distributed to Fairchild (FTG) and Xalapa (XAL). In 2011, F. Nicolalde-Morejón and S. Avendaño designated a lectotype held at XAL; the 2022 monograph dates the collection to 21 May 1997, at about 1,737 m. The World List of Cycads gives “May 1999”, a date that cannot be right for a plant described in 1997.

Relationships

The authors of 1997 thought it most likely allied to Ceratozamia matudae, because both have long cone stalks, and they spoke of a “matudae complex” of long-stalked populations ranging from Chiapas into central Oaxaca. They also compared its large, arching leaves with those of the large-leaved forms of Ceratozamia mexicana. The phylogeny of the genus published in 2023 by Habib and colleagues, based on 3,954 nuclear genes from 30 species, supports that first intuition: Ceratozamia mixeorum and Ceratozamia matudae form the Matudae clade, which is sister to all the other species of the genus. An earlier study had placed the two species in different clades.

Etymology and history

The Latin epithet mixeorum, “of the Mixes”, honours the Mixe people, who live in the region where the species is endemic, the Sierra Mixe of Oaxaca (original description; The World List of Cycads, after Haynes 2022).

The original description tells how little was known at first: the species had been seen only in the cloud forest covering the tops of two neighbouring mountains at the eastern end of the Sierra Norte, between 1,440 and 1,895 m. During their visit in May 1997, the authors estimated the population at 500 to 1,000 plants, with many seedlings and plants of all ages. They deliberately withheld the exact locality to protect it from collectors, and no plant was then known in cultivation. The 2022 monograph now cites specimens from six municipalities, including one collected at 2,147 m in 2011.

Common names

No English name is recorded. The original description gives the local name “carrete” (ox cart), because children play with the male cones like a little cart; the 2022 monograph and Species+ record the same name.

In the wild

According to the 2022 monograph, Ceratozamia mixeorum is endemic to the southern part of the Sierra Norte of Oaxaca, in the Mixe highlands, where it grows on karst rocks in cloud forest and oak forest between 1,170 and 2,150 m. The specimens examined come from the municipalities of San Juan Juquila Mixes, Santa María Tepantlali, Totontepec Villa de Morelos, San Pedro Ocotepec, Guevea de Humboldt and Santa María Guienagati. The monograph names it, with Ceratozamia zaragozae, as one of the two species of the genus that grow highest.

The original description gives a precise picture of its habitat: very steep, heavily shaded slopes facing east and west, with pockets of primary forest surrounded by coffee plantations and secondary growth. The upper canopy includes Weinmannia pinnata, Liquidambar styraciflua, Cyathea mexicana, Clethra mexicana and Quercus excelsa, and the trees are laden with epiphytes, mainly orchids and bromeliads. The soil is a light-coloured, crumbly, stony clay of pH 5, with outcrops of sedimentary rock, and rain falls all year round. Ceratozamia mixeorum is the dominant shrub of the understorey.

No study of its pollination or population dynamics has been published.

Conservation status and regulation

Ceratozamia mixeorum is assessed as Endangered (EN) on the IUCN Red List, in an assessment by J.D. Bösenberg published in 2022, under criteria A2acd+4acd; B1ab(i,ii,iii,iv,v): a past and projected decline of the population, and a small range in which every indicator is declining. The category is given by The World List of Cycads and by the Red List data distributed through GBIF (checked on 30 October 2026); the 2022 monograph cites the same category with slightly different criteria (A2cd+4cd; B1ab(ii,iii,v)).

As early as 1997, the authors noted that the type locality was being cleared and planted almost to the summits; they saw a local ban on further clearing, intended to protect the watershed, as a likely benefit for the species.

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+, 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 mixeorum

No growing advice specific to Ceratozamia mixeorum has been published, and no grower has reported on it. Its habitat, a cool, constantly moist cloud forest with dense shade and an acid, stony clay soil, points to light shade, regular moisture and a free-draining, slightly acid mix. These pointers are drawn from the habitat described in 1997 and have not been confirmed by published trials.

Outdoor and in-ground cultivation

No outdoor planting has been documented anywhere. Its long, drooping leaves and its cones on long stalks need room around the plant.

Container cultivation

No container-grown plant has been documented. A deep pot suits the taproot of Ceratozamia; a mineral, free-draining mix with some organic matter would reflect its habitat.

In cultivation in the UK, US and Australia

BGCI PlantSearch lists only two gardens for this species, both in Mexico: the Francisco Javier Clavijero botanic garden in Xalapa and the Jardín Etnobotánico de Oaxaca (queried on 30 October 2026). No British, American or Australian garden declares it, and the online catalogue of Montgomery Botanical Center (Coral Gables, Florida), rich in Ceratozamia, has none under this name.

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. The original description notes that seedlings usually start with a first leaf of four leaflets. Its branched trunks suggest that offsets could be taken, but no source describes it. 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 mixeorum. Growing up to more than 2,000 m, it is a cool-climate species by the standards of the genus, but no observation shows whether it tolerates frost.

Mediterranean and European experience

No cultivation result has been published in Europe, in the ground or in a pot. 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 backed by a trial have been published. In the UK it would be a plant for a heated glasshouse.

Toxicity and precautions

No toxicity study specific to Ceratozamia mixeorum 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 only reported use is as a toy: according to the original description and the 2022 monograph, children play with the male cones, hence the name “carrete”. No food or medicinal use is recorded.

Frequently asked questions

Where does the name mixeorum come from?

From the Mixe people. The Latin epithet means “of the Mixes” and honours the inhabitants of the Sierra Mixe, in Oaxaca, the only region where the species grows.

How can I recognise Ceratozamia mixeorum?

By its cones on very long stalks, up to 23.5 cm for the female cone, which hangs down when ripe. Its large, drooping leaves have a very prickly petiole.

How does it differ from Ceratozamia whitelockiana?

By its prickles and its cones. Ceratozamia whitelockiana has few prickles on the petiole, none on the axis, and a female cone on a short stalk.

Why is it called “carrete”?

Because children use it as a toy. They play with the male cones like a little ox cart, according to the authors of the description.

Is it endangered?

Yes. The IUCN has assessed it as Endangered since 2022: the forests of the Sierra Mixe are being cleared for coffee and crops.

Is it hardier than other Ceratozamia?

Nobody knows. It grows higher than most species, up to 2,150 m, but no cold trial has been published.

Can I buy one?

Only as a cultivated plant with its paperwork, and it is very rarely offered: no British, American or Australian garden declares it. The whole genus is in CITES Appendix I and Annex A of the EU regulation, seeds included.

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 mixeorum: https://cycadlist.org/scientific_name/38 — authors, publication date, lectotype, range, IUCN status and criteria, 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 mixeorum: https://api.gbif.org/v1/species/207874459 — accepted name, place of publication, south-western Mexico. Kew data, the basis of POWO, distributed by GBIF; consulted on 30 October 2026.
• The Cycad Society, copy of the original description of Ceratozamia mixeorum: https://www.cycad.org/documents/descriptions/Ceratozamia/Ceratozamia-mixeorum.pdf — description, type, habitat, population, local name, relationships. Specialist society, faithful copy of the primary source; reread on 30 October 2026.
• PubMed Central, monograph of Ceratozamia (PhytoKeys 208): https://pmc.ncbi.nlm.nih.gov/articles/PMC9849018/ — description, lectotype, range, altitude, habitat, common name, use, status, comparison with Ceratozamia whitelockiana. Peer-reviewed article, open access.
• PubMed Central, Phylotranscriptomics shed light on intrageneric relationships and historical biogeography of Ceratozamia (2023): https://pmc.ncbi.nlm.nih.gov/articles/PMC9921377/ — Matudae clade (Ceratozamia matudae and Ceratozamia mixeorum), sister to the rest of the genus. Peer-reviewed article, open access.
• Species+ (UNEP-WCMC), Ceratozamia mixeorum: https://speciesplus.net/species#/taxon_concepts/16337/legal — CITES Appendix I since 1 August 1985 (listing of the genus), Annex A in the European Union, Spanish name “carrete”. Official CITES and EU database; checked on 30 October 2026.
• BGCI PlantSearch: https://plantsearch.bgci.org/ — two Mexican gardens 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

• Chemnick, J., Gregory, T.J. & Salas-Morales, S. (1997, published 1998). Ceratozamia mixeorum (Zamiaceae), a new species from Oaxaca, Mexico with comments on distribution, habitat, and species relationships. Phytologia 83(1): 47–52. [Original description: diagnosis, description, type, habitat, population, local name, relationships.]
• Nicolalde-Morejón, F. & Avendaño, S. (2011). Lectotypification of Ceratozamia mixeorum (Zamiaceae). Revista Mexicana de Biodiversidad 82: 1032–1033. [Designation of the lectotype, cited by The World List of Cycads and 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, common name, use, status; open access.]
• Habib, S., Gong, Y., Dong, S., Lindstrom, A., Stevenson, D.W., Wu, H. & Zhang, S. (2023). Phylotranscriptomics shed light on intrageneric relationships and historical biogeography of Ceratozamia (Cycadales). Plants 12(3): 478. https://doi.org/10.3390/plants12030478 [Phylogeny of the genus; open access.]
• Bösenberg, J.D. (2022). Ceratozamia mixeorum. The IUCN Red List of Threatened Species 2022: e.T42183A69822673. https://doi.org/10.2305/IUCN.UK.2022-1.RLTS.T42183A69822673.en [Red List assessment; category confirmed by GBIF.]
• 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.]