Ceratozamia osbornei

Ceratozamia osbornei is a large cycad endemic to Belize, in Central America, where it grows on limestone rocks in the evergreen tropical forests of the Maya Mountains, between 200 and 750 m (about 660 to 2,460 ft). Described in 2022 and named after the cycad specialist Roy Osborne, it is the only species of the genus Ceratozamia known from Belize: the Belizean plants were previously identified as Ceratozamia robusta, a species of Mexico and Guatemala. Its cones are covered in a wine-red to purple down. The IUCN has not yet assessed it, and its status as a species has been questioned.

Key facts about Ceratozamia osbornei

  • Accepted name: Ceratozamia osbornei D.W.Stev., Mart.-Domínguez & Nic.-Mor. (2022), accepted by The World List of Cycads (version 2026.08.15) and by the World Checklist of Vascular Plants (WCVP, the database behind POWO, read via GBIF); its specific status was questioned by J.L. Haynes in 2023
  • Former names and synonyms: no synonym; the plants of Belize were previously identified as Ceratozamia robusta
  • Family: Zamiaceae, order Cycadales
  • Common names: none recorded
  • Natural range: Belize (Cayo and Toledo districts, Maya Mountains), 200 to 750 m
  • IUCN status: Not Evaluated; insufficient data according to 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 evergreen tropical forest; no published growing advice
  • Habit and adult size: trunk usually lying on the ground, 0.3 to 2 m long; 12 to 50 leaves, 0.9 to 3 m long; male cone 60 to 80 cm long
  • In the UK, US and Australia: grown at Fairchild Tropical Botanic Garden and declared to BGCI PlantSearch by one other American garden; none in the UK or Australia (see In cultivation)
  • Toxicity: no data for the species; treat it as poisonous (see Toxicity and precautions)

How to recognise Ceratozamia osbornei

What sets Ceratozamia osbornei apart is its cones: the female cone scales are covered in abundant purple to wine-red hairs, present at every stage of the cone; the female cone ends in a drawn-out point and has up to 12 vertical rows of up to 31 scales; and the scales of the male cone have a long sterile tip, 6.5 to 8 mm. Without cones, the plant looks very much like Ceratozamia robusta. The 2022 monograph, in which the species was described, gives the following description:

  • Trunk: above ground, usually lying on the ground, 30 to 200 cm long and 20 to 40 cm in diameter; persistent, triangular, reddish-brown cataphylls. The monograph counts it among the four species of the genus with an arborescent habit.
  • Leaves: 12 to 50, ascending, 90 to 300 cm long; brown with whitish-grey hairs when they emerge, then hairless. The petiole, 75 to 100 cm long, greenish brown or dark brown, then green, carries 20 to 40 stout prickles 2 to 4.5 mm long.
  • Leaflets: 26 to 51 pairs, lance-shaped, papery, dark green and hairless, with a drawn-out, symmetrical tip; the middle ones measure 30 to 45 cm by 2.5 to 4 cm. Their points of attachment are brown on young leaves.
  • Male cones: single, cylindrical, upright, very large, 60 to 80 cm long and 7 to 9 cm across, green with wine-red hairs, then greenish yellow with wine-red to purple hairs; stalk 7 to 11 cm long.
  • Female cones: single, cylindrical, upright, 30 to 50 cm long and 9 to 14 cm across, green and covered in dark purple hairs, with a drawn-out tip; stalk 12 to 20 cm long. They carry 108 to 280 scales with straight horns.
  • Seeds: oval, large, 3 to 4.5 cm long, with pinkish-white flesh before ripening, light brown when ripe.

The same monograph calls the male cone of Ceratozamia robusta, up to 70 cm long, the largest in the genus, while giving 60 to 80 cm for that of Ceratozamia osbornei; the two statements are not reconciled.

Hybrids

No natural or garden hybrid has been documented.

Possible confusion

According to the 2022 monograph, Ceratozamia osbornei most resembles two large species, from which it differs by its cones:

  • Ceratozamia robusta, of Chiapas and Guatemala: dark green female cone with sparse blackish hairs when ripe; this is the species with which the Belizean plants were identified.
  • Ceratozamia subroseophylla, of southern Veracruz (the 2022 monograph also included plants from Tabasco, assigned to Ceratozamia gigantea since 2024): female cone with a short point and scales with a pinkish base and dark brown to reddish-brown hairs.

Without cones, origin is the best clue: no other species of the genus is known from Belize. A cultivated plant without a known origin cannot be identified with certainty.

Taxonomy

Ceratozamia osbornei is accepted by The World List of Cycads and by the WCVP, the database behind POWO (read via GBIF on 30 October 2026), which records it from Belize only. It was described by D.W. Stevenson, L. Martínez-Domínguez and F. Nicolalde-Morejón in the monograph of the genus published in 2022 in PhytoKeys (208: 68–69, figures 5, 6 and 22).

The Ceratozamia of Belize

Before 2022, the Ceratozamia of Belize were identified as Ceratozamia robusta: the 2009 description of Zamia decumbens, from the Maya Mountains, reports Ceratozamia robusta throughout the range of that species. The 2022 monograph explains why it separated them. Ceratozamia robusta is the most widespread species of the genus, from central Chiapas to Guatemala, but herbarium specimens from Guatemala are sterile and few, which has led to ambiguous or conflicting identifications. Recently collected cones from Belizean plants showed features that distinguish them from the plants of Mexico and Guatemala, hence the description of Ceratozamia osbornei. The authors call for population studies to measure genetic differentiation and gene flow between the two species.

The World List of Cycads now limits Ceratozamia robusta to Chiapas and Guatemala (Alta Verapaz, Petén, Quiché, Huehuetenango and Izabal), without Belize, and the WCVP places it in Guatemala and south-eastern Mexico only. In 2023, Jody Haynes questioned the specific status of Ceratozamia osbornei in his critical review of the monograph, published in Phytotaxa. The abstract of that review also reports variation between individuals and with age in cone colour and in the shape of the female cone tip, two of the features used in the diagnosis of Ceratozamia osbornei. The World List of Cycads nevertheless keeps it as an accepted species.

Type

The holotype was collected on 6 April 1992 by B.K. Holst (no. 4105) in the south-western Maya Mountains, in Toledo District. It is held at the New York Botanical Garden herbarium (NY), with an isotype at the Missouri Botanical Garden (MO). The paratypes were collected between 1971 and 2008 in Cayo and Toledo districts.

Etymology and history

The epithet honours Roy Osborne for his remarkable contribution to knowledge of cycad diversity worldwide, and in particular for his work on The World List of Cycads since its inception (2022 monograph, cited by The World List of Cycads). Roy Osborne is one of the three editors of that reference checklist.

The species is grown at Fairchild Tropical Botanic Garden, in Florida: the monograph illustrates its immature and mature female cone with photographs taken in that garden, and part of the description and of the plate is based on a plant cultivated there.

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 osbornei is endemic to Belize, where it grows in evergreen tropical forest, on karst rocks rich in organic matter, between 200 and 750 m. The World List of Cycads records it in Cayo and Toledo districts. One paratype collected in Toledo in 1976 is labelled “800–1,200 m”, above that range.

In the same mountains grows Zamia decumbens, and the 2009 description of that species reports the two cycads growing together at one locality in northern Cayo District. According to the authors of the monograph, some populations of Ceratozamia osbornei have more than 100 plants. No study of its pollination or cone calendar has been published.

Conservation status and regulation

Ceratozamia osbornei 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 consider the data insufficient for an assessment, while noting that some populations exceed 100 plants.

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 osbornei

No growing advice specific to Ceratozamia osbornei has been published, and no grower has reported on it. Its presence at Fairchild Tropical Botanic Garden, in southern Florida, shows that it grows and produces cones there, but the garden publishes no growing notes.

Its habitat, a lowland tropical rainforest on limestone, points to warmth, partial shade and a free-draining, humus-rich mix. Its size, with leaves up to 3 m long, needs a lot of room. These pointers are drawn from the habitat and the description and have not been confirmed by published trials.

Outdoor and in-ground cultivation

Only frost-free, warm and humid climates suit it outdoors. Fairchild, in Coral Gables, Florida, is the only documented garden where it produces cones, but whether its plants grow outdoors or under cover is not stated.

Container cultivation

Young plants can be grown in a large, deep pot with a free-draining mix rich in organic matter; adults, with their long leaves and large cones, are better planted out in a heated glasshouse or a tropical garden.

In cultivation in the UK, US and Australia

In the United States, Fairchild Tropical Botanic Garden (Coral Gables, Florida) holds the species: the 2022 monograph photographed its cones there, and the garden lists it in its online catalogue (consulted on 19 October 2026). BGCI PlantSearch lists one garden under this name, the University of Hawaii at Hilo botanical garden (queried on 30 October 2026); the online catalogue of Montgomery Botanical Center has no accession under this name. No British or Australian garden declares it.

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 osbornei. It is a plant of lowland tropical forest, to be kept frost-free until documented trials exist.

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. Hardiness figures published for “Ceratozamia robusta” by commercial websites cannot be transferred to it, since the origin of the plants concerned is not given.

United Kingdom, United States and Australia

No dated cold record and no commercial hardiness rating have been published. In the UK it is a plant for a heated glasshouse.

Toxicity and precautions

No toxicity study specific to Ceratozamia osbornei 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

Is Ceratozamia osbornei a recognised species?

Yes, for now. The World List of Cycads and the WCVP accept it as a species in its own right. Jody Haynes questioned its status in 2023, but the reference checklist has not placed it in synonymy.

Are there other Ceratozamia in Belize?

No. It is the only species of the genus known from Belize; Ceratozamia robusta, with which it was confused, is not recorded there by The World List of Cycads or the WCVP.

How can I tell it from Ceratozamia robusta?

By its cones. Those of Ceratozamia osbornei are covered in purple to wine-red hairs, and the female cone has a drawn-out tip; that of Ceratozamia robusta is dark green with sparse blackish hairs.

Who is Roy Osborne?

A cycad specialist and one of the three editors of The World List of Cycads. The species was dedicated to him in 2022 for his contribution to knowledge of cycads.

Is it endangered?

Nobody knows. The IUCN has not assessed it, for lack of data; some populations exceed 100 plants. Like the whole genus, it is in CITES Appendix I.

Can it take frost?

There is no evidence that it can. No trial exists; it is a plant of lowland tropical forest, to be kept frost-free.

How large does it grow?

Large. The trunk, usually lying on the ground, reaches 2 m, the leaves up to 3 m, and the male cone 60 to 80 cm.

Further reading on Succulentes

Sources

Reference sites

  • The World List of Cycads (version 2026.08.15), Ceratozamia osbornei: https://cycadlist.org/scientific_name/1022 — authors, publication, type, range (Cayo, Toledo), IUCN status (Not Evaluated), etymology. Checklist of the IUCN Cycad Specialist Group, reliable; reread on 30 October 2026.
  • The World List of Cycads (version 2026.08.15), Ceratozamia robusta: https://cycadlist.org/scientific_name/41 — range limited to Chiapas and Guatemala, without Belize. Reference checklist; reread on 30 October 2026.
  • World Checklist of Vascular Plants (WCVP, Royal Botanic Gardens, Kew), via GBIF, Ceratozamia osbornei: https://api.gbif.org/v1/species/209738047 — accepted name, place of publication (PhytoKeys 208: 68, 2022), Belize; Ceratozamia robusta: https://api.gbif.org/v1/species/207874450 — Guatemala and south-eastern 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/ — original description of the species, type and paratypes, habitat, status, discussion of the Belizean plants and of Ceratozamia robusta, photographs taken at Fairchild. Peer-reviewed article, open access.
  • Journal of the Botanical Research Institute of Texas, original description of Zamia decumbens (open-access PDF): https://cycadlist.org/storage/references/open/d384fe59-2aca-4441-a57f-0ab19a8029d1.pdf — Ceratozamia identified as Ceratozamia robusta throughout the range of Zamia decumbens in Belize. Peer-reviewed journal, 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/ — one garden declaring the species (University of Hawaii at Hilo). Global database of garden lists; queried on 30 October 2026.
  • Fairchild Tropical Botanic Garden, Garden Explorer: https://fairchild.gardenexplorer.org/ — online catalogue of the living collection (updated on 16 October 2026). Catalogue kept by the garden; consulted on 19 October 2026.

Bibliography

  • 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 [Original description of Ceratozamia osbornei (pages 68–69); open access.]
  • Haynes, J.L. (2023). Critical review of “Monograph of Ceratozamia (Zamiaceae, Cycadales): an endangered genus” published in PhytoKeys 208: 1–102 (2022). Phytotaxa 612(2): 159–200. https://doi.org/10.11646/phytotaxa.612.2.4 [Questions the specific status of Ceratozamia osbornei; abstract.]
  • Calonje, M.A., Meerman, J., Griffith, M.P. & Hoese, G. (2009). A new species of Zamia (Zamiaceae) from the Maya Mountains of Belize. Journal of the Botanical Research Institute of Texas 3(1): 31–41. [Identification of the Belizean Ceratozamia as Ceratozamia robusta at the time.]
  • 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 etymologies 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.]