Ceratozamia norstogii

Ceratozamia norstogii is a cycad of the mountains of western Chiapas and neighbouring Oaxaca, in southern Mexico, where it grows on limestone rocks in pine-oak forest between 800 and 1,650 m (about 2,620 to 5,410 ft). Described in 1982 from a plant collected in 1925, it is one of the easiest species of the genus Ceratozamia to recognise: its copper-coloured leaf stalks are twisted, according to the 2022 monograph, and its very narrow, leathery leaflets are rolled into a gutter. The IUCN assesses it as Endangered.

Key facts about Ceratozamia norstogii

• Accepted name: Ceratozamia norstogii D.W.Stev. (1982), 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• Former names and synonyms: none; recognised before 1982 under two unpublished herbarium names
• Family: Zamiaceae, order Cycadales
• Common names: none recorded
• Natural range: Mexico, western Chiapas (municipality of Cintalapa) and eastern Oaxaca (San Miguel Chimalapa, Santo Domingo Zanatepec), 800 to 1,650 m
• IUCN status: Endangered (EN A2acd; B1ab(iii,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 measured data (see Cold hardiness)
• Light and soil: in the wild, karst rocks in pine-oak forest and in the transition between pine forest and oak forest, a relatively dry habitat for the genus; no published growing advice
• Habit and adult size: above-ground trunk 30 to 60 cm long (less than 50 cm in the original description); 5 to 48 leaves, 0.5 to 1.3 m long (1 to 2 m in the original description)
• In the UK, US and Australia: declared to BGCI PlantSearch by 11 American and 4 Australian gardens; none in the UK (see In cultivation)
• Toxicity: no data for the species; treat it as poisonous (see Toxicity and precautions)

How to recognise Ceratozamia norstogii

According to the 2022 monograph, Ceratozamia norstogii is easily identified by its twisted petiole and leaf axis. Its linear, leathery leaflets are so strongly rolled upwards that they look like gutters, and end in a sharp point. The monograph describes it as follows:

• Trunk: above ground, 30 to 60 cm long and 20 to 40 cm in diameter, upright then lying down; persistent, long-triangular, reddish-brown, woolly cataphylls.
• Leaves: 5 to 48, ascending, 50 to 126 cm long; coppery brown with whitish-grey hairs when they emerge, then hairless. The petiole, 10 to 49 cm long, coppery and twisted, carries 30 to 60 stout prickles 1 to 3 mm long; the axis, 40 to 88 cm long, is also coppery, twisted and prickly.
• Leaflets: 33 to 91 pairs, linear, leathery, strongly rolled, green with a yellowish-green base, glaucous beneath, with a sharp, symmetrical tip; the middle ones measure 14 to 48 cm long but only 2 to 4.6 mm wide, and are spaced 0.2 to 1.3 cm apart.
• Male cones: single, cylindrical, upright, 13 to 25 cm long and 3 to 8 cm across, brown with reddish-brown hairs, then yellowish green to cream; stalk 2 to 5.5 cm long.
• Female cones: single, cylindrical, upright, 21 to 35 cm long and 8.5 to 10.5 cm across, greyish green and covered in blackish hairs when ripe, with a drawn-out tip; stalk 4.8 to 9 cm long. The 42 to 63 scales carry two straight horns.
• Seeds: oval, 2 to 3.5 cm long, with pinkish-white flesh before ripening, light brown when ripe.

The original description (Stevenson, 1982), based largely on herbarium specimens and cultivated plants, differs on a key point: it gives a straight petiole and axis, and even uses this feature to separate Ceratozamia norstogii from Ceratozamia zaragozae, whose petiole and axis are twisted. As early as 1986, however, the description of Ceratozamia euryphyllidia by Stevenson, Sabato and Vázquez Torres described the axis of both species as twisted, as does the 2022 monograph; no published source explains the change. The other figures of 1982 are: a short trunk, under 50 cm; leaves 1 to 2 m long, densely hairy when young; a petiole 20 to 30 cm long, prickly mainly near the base; 50 to 80 leaflets on each side, 20 to 50 cm by 3 to 7 mm (up to 10 mm), with five or six veins, so strongly rolled that they become almost tubular when dry; a tawny-brown male cone 20 to 25 cm long; an olive-green female cone 20 to 40 cm long; and white seeds, 2 to 3.5 cm long, when ripe.

Hybrids

No natural or garden hybrid has been documented.

Possible confusion

Only one other species of the genus has a twisted petiole and axis: Ceratozamia zaragozae, of San Luis Potosí, some 900 km further north according to the 1986 study. According to the 2022 monograph, it differs in its unarmed petiole (with abundant, stout prickles in Ceratozamia norstogii) and its membrane-thin leaflets (leathery in Ceratozamia norstogii). Their origin is usually enough to tell them apart. The 1982 description contrasted them differently: straight petiole and axis and tapering leaflet tips in Ceratozamia norstogii, twisted petiole and axis and abruptly pointed leaflets in Ceratozamia zaragozae, which it considered its closest relative.

Other species of southern Mexico have narrow leaflets, such as Ceratozamia mirandae and Ceratozamia alvarezii in Chiapas, but their axis is not twisted and their leaflets are papery, without the gutter-like rolling of Ceratozamia norstogii.

Taxonomy

Ceratozamia norstogii 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-eastern and south-western Mexico. It was described by Dennis W. Stevenson in Brittonia (34(2): 181–184, 1982), in an article entitled “A new species of Ceratozamia (Zamiaceae) from Chiapas, Mexico”.

According to Stevenson, three botanists had already recognised the species as new without ever describing it: J.N. Rose, who labelled Purpus’s specimens with an unpublished name honouring the collector; P.C. Standley, who independently named after Alice Eastwood specimens taken by Eric Walther from plants cultivated in California; and C.J. Chamberlain, who used Rose’s manuscript name. To avoid any confusion between these two herbarium names, Stevenson chose an entirely new one.

The holotype is a female plant collected in March–April 1925 by C.A. Purpus (no. 6), in shady forests in Chiapas. It is held at the New York Botanical Garden herbarium (NY), with isotypes at F, MO and US according to the 2022 monograph (the original description cites only US and fragments at F). The species thus waited more than half a century in herbaria before being described.

In the 2023 phylogeny of the genus by Habib and colleagues, Ceratozamia norstogii gives its name to the norstogii subclade of the Miqueliana clade, together with Ceratozamia alvarezii, Ceratozamia mirandae, Ceratozamia chimalapensis and Ceratozamia vovidesii. The study notes that Ceratozamia norstogii, Ceratozamia alvarezii and Ceratozamia mirandae are restricted to coniferous forest, and describes Ceratozamia norstogii as adapted to a shady, high-altitude, seasonally dry forest.

Etymology and history

The epithet honours Knut J. Norstog (1921–2003), an American botanist at Fairchild Tropical Botanic Garden in Coral Gables, Florida, and a leading student of cycad biology; Stevenson thanked him for his contribution to the understanding of cycads and for having stirred his own interest in the group (original description; The World List of Cycads, after Haynes 2022).

The original description shows that the species was grown in the United States long before it was named: at the Sharp Estate in Coronado, near San Diego (plants taken from the wild by Edward Howard; specimens by C.J. Chamberlain in 1937 and 1940), at the Doheny conservatory in San Marino, near Los Angeles (plants from northern Chiapas; specimen of 1939), in the conservatory of Golden Gate Park in San Francisco (1929), and at Fairchild Tropical Garden in Miami (accession 69-421, which produced a male cone in 1971). The female cone and seeds illustrated in 1982 came from a plant of that Fairchild accession.

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 norstogii lives in the mountains of Chiapas and Oaxaca, on karst rocks, in pine-oak forest and in the transition between pine forest and oak forest, between 800 and 1,650 m. The specimens examined come from the municipality of Cintalapa in Chiapas and from San Miguel Chimalapa and Santo Domingo Zanatepec in Oaxaca. In 1986, Stevenson, Sabato and Vázquez Torres described the pine-oak forest where it and Ceratozamia zaragozae grow as the driest habitat for the genus, and gave these two species the most leathery leaflets in Ceratozamia.

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

Conservation status and regulation

Ceratozamia norstogii is assessed as Endangered (EN) on the IUCN Red List, in an assessment by J.D. Bösenberg published in 2022, under criteria A2acd; B1ab(iii,v): an observed population decline linked to habitat loss and collecting, and a small range in which habitat and the number of adults are 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 under other criteria (A2abd; B1ab(iii,iv,v); C1).

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 norstogii

No growing advice specific to Ceratozamia norstogii has been published, and no grower has reported on it. It is nevertheless held by 21 public gardens worldwide, and it has been grown in California since at least 1929.

Its habitat, limestone rocks in a relatively dry pine-oak forest at mid-altitude, points to filtered light and a very free-draining mix. These pointers are drawn from the habitat and have not been confirmed by published trials.

Outdoor and in-ground cultivation

In Melbourne, the census of the Royal Botanic Gardens Victoria (consulted on 19 October 2026) lists three plants in an outdoor bed, besides one in the Cycad House; the garden publishes no information on how the outdoor plants fare. Several of the American gardens that hold it are in frost-free or mild areas (southern Florida, coastal California, Hawaii), but none says whether its plants are outdoors.

Container cultivation

Its moderate size, with leaves rarely more than 1.3 m long in the wild, suits a large pot. A mineral, very free-draining mix reflects the limestone rocks it grows on; keep it on the dry side in winter.

In cultivation in the UK, US and Australia

BGCI PlantSearch lists 21 gardens for this species (queried on 30 October 2026). In the United States, these are Montgomery Botanical Center (Coral Gables, Florida; 2 accessions in its online catalogue), Fairchild Tropical Botanic Garden, Marie Selby Botanical Gardens (Sarasota), the Huntington, Ganna Walska Lotusland, the San Diego Zoo, the United States Botanic Garden (Washington), Phipps Conservatory and Botanical Gardens (Pittsburgh), the John Fairey Garden, Honolulu Botanical Gardens and the University of Hawaii at Hilo botanical garden. In Australia, the Royal Botanic Garden Sydney, the Royal Botanic Gardens Victoria (Melbourne), the Botanic Garden of Adelaide and the Cairns Botanic Gardens declare it. No British garden lists it. Elsewhere, it is held in Mexico (the Faustino Miranda botanic garden in Chiapas and the Francisco Javier Clavijero botanic garden in Xalapa), Germany, the Netherlands, China and Singapore.

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. At Fairchild, accession 69-421 produced a male cone in 1971, and the female cone and seeds illustrated in 1982 came from the same accession. 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 measured cold-hardiness value exists for Ceratozamia norstogii. Its pine-oak forest, up to 1,650 m, does not by itself tell how much frost it can take.

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. The only outdoor plants documented are the three in Melbourne, without any record of winter temperatures or damage. In the UK it is a plant for a frost-free glasshouse.

Toxicity and precautions

No toxicity study specific to Ceratozamia norstogii 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

How can I recognise Ceratozamia norstogii?

By its twisted, copper-coloured petiole and axis, according to the 2022 monograph (the 1982 description called them straight). Its very narrow leaflets, less than 5 mm wide and rolled into a gutter, are also distinctive.

How does it differ from Ceratozamia zaragozae?

By its prickles and its leaflet texture. Ceratozamia zaragozae, of San Luis Potosí, also has a twisted axis, but its petiole is unarmed and its leaflets are membrane-thin.

Where does it grow?

In the mountains of western Chiapas and eastern Oaxaca, in Mexico. It grows on limestone rocks in pine-oak forest, between 800 and 1,650 m.

Who was Norstog?

Knut J. Norstog (1921–2003), an American botanist at Fairchild Tropical Botanic Garden in Florida, who specialised in cycad biology.

Is it endangered?

Yes. The IUCN has assessed it as Endangered since 2022, and the whole genus is in CITES Appendix I.

Can it take frost?

Nobody knows. No trial has been published; keep it frost-free until there is evidence.

Is it poisonous?

Assume so. No analysis exists for the species, but the cycads studied contain toxins that seriously harm the liver and nervous system, above all in the seeds.

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 norstogii: https://cycadlist.org/scientific_name/40 — author, publication, type (Purpus, 1925), 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 norstogii: https://api.gbif.org/v1/species/207874455 — accepted name, place of publication, south-eastern and 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 norstogii: https://www.cycad.org/documents/descriptions/Ceratozamia/Ceratozamia-norstogii.pdf — diagnosis, description, type and paratypes, cultivated plants, comparison with Ceratozamia zaragozae, history of the herbarium names. Specialist society, faithful copy of the primary source; reread on 30 October 2026.
• The Cycad Society, copy of the original description of Ceratozamia euryphyllidia (Brittonia, 1986): https://www.cycad.org/documents/descriptions/Ceratozamia/Ceratozamia-euryphyllidia.pdf — twisted axis and leathery leaflets of Ceratozamia norstogii and Ceratozamia zaragozae, driest habitat of the genus. Specialist society, faithful copy of a primary source.
• PubMed Central, monograph of Ceratozamia (PhytoKeys 208): https://pmc.ncbi.nlm.nih.gov/articles/PMC9849018/ — description, type, range, altitude, habitat, status, comparison with Ceratozamia zaragozae. 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/ — norstogii subclade, coniferous forest. Peer-reviewed article, open access.
• Species+ (UNEP-WCMC), Ceratozamia norstogii: https://speciesplus.net/species#/taxon_concepts/28161/legal — CITES Appendix I since 1 August 1985 (listing of the genus), Annex A in the European Union. Official CITES and EU database; checked on 30 October 2026.
• BGCI PlantSearch: https://plantsearch.bgci.org/ — 21 gardens declaring the species, including 11 in the United States and 4 in Australia. Global database of garden lists; queried on 30 October 2026.
• Montgomery Botanical Center, living collection: https://www.montgomerybotanical.org/research/living-collection/ — 2 accessions of the species in its BG-BASE catalogue. Specialist cycad garden; catalogue queried on 30 October 2026.
• Royal Botanic Gardens Victoria, Living Collections Census: https://data.rbg.vic.gov.au/rbgcensus/ — Ceratozamia norstogii in the Cycad House and in an outdoor bed at Melbourne Gardens. Census kept by the garden; consulted on 19 October 2026 (application unavailable on 30 October 2026 during a software upgrade).

Bibliography

• Stevenson, D.W. (1982). A new species of Ceratozamia (Zamiaceae) from Chiapas, Mexico. Brittonia 34(2): 181–184. https://doi.org/10.2307/2806372 [Original description: diagnosis, description, type and paratypes, cultivated plants, comparison with Ceratozamia zaragozae, history of the herbarium names.]
• Stevenson, D.W., Sabato, S. & Vázquez Torres, M. (1986). A new species of Ceratozamia (Zamiaceae) from Veracruz, Mexico with comments on species relationships, habitats, and vegetative morphology in Ceratozamia. Brittonia 38(1): 17–26. [Description of Ceratozamia euryphyllidia; comparison of species groups and habitats.]
• 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, 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 norstogii. The IUCN Red List of Threatened Species 2022: e.T42102A69822880. https://doi.org/10.2305/IUCN.UK.2022-1.RLTS.T42102A69822880.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.]