Ceratozamia hildae

Ceratozamia hildae is a small cycad of east-central Mexico, endemic to the Sierra Gorda on the border between the states of San Luis Potosí and Querétaro, where it grows on limestone rocks in evergreen tropical forest between 300 and 1,200 m (about 980 to 3,940 ft). This species of the genus Ceratozamia is easy to recognise: its thin leaflets are gathered in small clusters along a slender leaf axis, which gives it the look of a bamboo and its English name, “bamboo cycad”. Described in 1979 from plants grown in Louisiana, it is assessed as Critically Endangered by the IUCN, yet it is one of the most widely grown species of the genus, especially in the United States.

Key facts about Ceratozamia hildae

  • Accepted name: Ceratozamia hildae G.P.Landry & M.C.Wilson (1979), 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)
  • Former names and synonyms: none; sold in the horticultural trade as “hilda” before its description
  • Family: Zamiaceae, order Cycadales
  • Common names: bamboo cycad (English); “chamalillo” and “pata de gallo” in Querétaro (Spanish)
  • Natural range: Mexico, Sierra Gorda (San Luis Potosí and Querétaro), 300 to 1,200 m
  • IUCN status: Critically Endangered (CR A2acd, assessment published in 2022); the 2022 monograph of the genus gives Endangered (EN), citing an earlier listing
  • CITES and other protection: CITES Appendix I (whole genus, since 1985); Annex A in the European Union, seeds included
  • Documented hardiness: survives down to about −9 °C (15 °F) according to the University of Florida; one partly protected plant in the ground took −5 °C (23 °F) in Sicily in 2008 (see Cold hardiness)
  • Light and soil: partial shade by preference, tolerates moderate sun or deep shade; free-draining soil
  • Habit and adult size: short trunk, 10 to 20 cm, partly underground; 2 to 7 upright leaves, 0.95 to 2 m long
  • In the UK, US and Australia: declared by 6 British, 38 American and 6 Australian gardens to BGCI PlantSearch (see In cultivation)
  • Toxicity: no data specific to the species; treat it as poisonous, like all cycads (see Toxicity and precautions)

How to recognise Ceratozamia hildae

It is the only Ceratozamia whose leaflets are grouped in small bunches separated by bare stretches of the leaf axis. An adult plant can be identified by this feature alone, even without cones. The 2022 monograph of the genus describes it as follows:

  • Trunk: short, 10 to 20 cm long and 10 to 15 cm in diameter, partly underground, upright; reddish-brown cataphylls, covered in brown down when they emerge.
  • Leaves: 2 to 7, upright, 95 to 202 cm long; reddish brown and covered in greyish-white hairs when they emerge, then hairless. The petiole, 43 to 89 cm long, bears 2 to 12 tiny prickles; the axis is sometimes unarmed.
  • Leaflets: 16 to 56 in all, grouped in 5 to 11 clusters, oblong, thin and membranous, green and glaucous on both sides; median leaflets 14.5 to 24 cm long and 2.4 to 5 cm wide, with 6 to 15 cm between clusters.
  • Male cones: solitary, small, 8 to 12.5 cm long and 2 to 2.5 cm across, brown, then reddish brown.
  • Female cones: solitary, upright, 10 to 15 cm long and 6 to 9 cm across, green with brown to blackish hairs; scales with straight horns 3 to 5 mm long.
  • Seeds: egg-shaped, 1.3 to 2.3 cm long, pinkish white before ripening and light brown when ripe.

Young plants have less clearly clustered leaflets than adults, which can mislead at the seedling stage. The original description, made from cultivated plants, gives partly different figures: an egg-shaped to almost cylindrical trunk 9 to 15 cm tall; 5 to 20 leaves 1 to 1.5 m long with a spiny petiole; leaflets 7 to 22 cm long and 1 to 5 cm wide; a tawny-brown male cone 18 to 25 cm long; and an olive-green female cone 10 to 14 cm long on a stalk of 6 to 9 cm. The largest gaps with the monograph concern the number of leaves (5 to 20 against 2 to 7) and the length of the male cone (18 to 25 cm against 8 to 12.5 cm). Landry and Wilson stressed the papery texture of the leaflets and their consistent clustering, unmatched in the genus.

Hybrids

No natural hybrid is documented. Garden-made hybrids exist in collections: BGCI PlantSearch lists a Ceratozamia hildae × Ceratozamia kuesteriana at the Gardens of Golden Gate Park in San Francisco, and a Ceratozamia fuscoviridis × Ceratozamia hildae at the Huntington in San Marino, California. None of them has been described in a publication.

Possible confusion

An adult plant cannot be confused with any other Ceratozamia, thanks to its clustered leaflets. The two other small species of the same mountains have evenly spaced leaflets:

In 1983, the original description of Ceratozamia microstrobila (now a synonym of Ceratozamia latifolia) already separated these small eastern species with a simple key: clustered leaflets for Ceratozamia hildae, evenly spaced lance-shaped leaflets for the other. Mislabelled plants are the main risk in collections, particularly seedlings, whose leaflets are not yet clearly grouped.

Taxonomy

Ceratozamia hildae is accepted by The World List of Cycads and by the WCVP, which records its publication in Brittonia 31, page 422 (1979), and places it in north-eastern Mexico. The species has no synonym and its status is not disputed. It was described in 1979 by Garrie P. Landry, of Louisiana State University, and Marcia C. Wilson, under the title “A new species of Ceratozamia (Cycadaceae) from San Luis Potosí” (Brittonia 31(3): 422–424). At the time the genus was placed in the family Cycadaceae; it now belongs to the Zamiaceae.

The authors saw no close relative: the size of its leaflets falls within the range of Ceratozamia mexicana, but the consistent clustering of the leaflets and their papery texture set it apart from every other species. Four years later, Vovides and Rees placed it, with Ceratozamia zaragozae and Ceratozamia microstrobila, in a group of small eastern species with almost underground trunks, few small leaves and small cones.

Etymology and history

The epithet honours Hilda Guerra Walker, daughter of Luciano E. Guerra, a commercial plant collector from Mission, Texas, who imported the species in early 1960. From its introduction the plant was known in the trade as “hilda”, the name Guerra had chosen for his daughter; Landry and Wilson kept it in honour of his lifelong interest in cycads (original description, 1979). The World List of Cycads gives Luciano Guerra’s dates as 1923–2021.

Its description is unusual: the type was not collected in Mexico but taken from plants grown outdoors in a private garden in Baton Rouge, Louisiana. These plants had come from Larry Bussell, of Valrico, Florida, who had collected them several kilometres north of Xilitla, in San Luis Potosí. The holotype, a male specimen collected on 6 June 1976 by Garrie Landry (collection 76521), is kept at the Harvard University Herbaria (GH), with isotypes at MEXU, MICH, US, NY, FTG and LSU; a female specimen (Landry 75495, GH) was also examined. The species was therefore in American gardens for almost twenty years before it had a botanical name.

Common names

In English it is the “bamboo cycad”, a name already noted in the original description and used by Species+ and the University of Florida: the clustered leaflets on a slender axis recall bamboo foliage. In Mexico, the 2022 monograph records “chamalillo” and “pata de gallo” (“rooster’s foot”) in Querétaro, from a herbarium label; Species+ also lists “pata de gallo”. “Chamalillo” is also used for Ceratozamia latifolia in San Luis Potosí, so it is not specific to this species.

In the wild

Ceratozamia hildae is endemic to the Sierra Gorda, in the Sierra Madre Oriental, where San Luis Potosí meets Querétaro (The World List of Cycads cites both states). According to the 2022 monograph, it grows in evergreen tropical forest, on karst rocks, between 300 and 1,200 m.

The original description knew a single area, a few kilometres north of Xilitla, in southern San Luis Potosí: dense tropical rainforest on often steep slopes with much outcropping limestone. No study of its populations or pollination has been published.

Conservation status and regulation

Ceratozamia hildae is assessed as Critically Endangered (CR, criterion A2acd) on the IUCN Red List, in an assessment by J.D. Bösenberg, F. Nicolalde-Morejón and L. Martínez-Domínguez published in 2022; the category is given by The World List of Cycads and by the Red List data distributed through GBIF (checked on 30 October 2026). Criterion A2 reflects a marked recent decline of the populations, linked to habitat loss and collecting. The 2022 monograph cites an earlier listing as Endangered (EN, criteria A2abcd and B1ab(ii,iii,iv)); the 1979 description proposed no status.

Like the whole genus, it has been covered by CITES Appendix I since 1 August 1985, 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). Plants on sale should come from cultivated seed, with the documents to prove it.

This general information does not replace the official texts: check the regulations in force before buying or exchanging plants, ask the seller for proof of origin, and prefer plants raised from cultivated seed.

Growing Ceratozamia hildae

Ceratozamia hildae is considered easy and fast for a cycad. The University of Florida’s extension service (UF/IFAS, text by a member of the Cycad Society) says that it tolerates a wide range of climates and light levels, can mature in two to four years in good conditions, and grows best in partial shade, though it accepts moderate sun or deep shade. According to the same source, its leaves reach 1.5 to 2 m (5 to 7 ft), depending on how much light they receive.

It needs a free-draining medium: UF/IFAS notes that it likes a little more moisture than many cycads and tolerates dry spells, but is sensitive to root rot and should never sit in saturated soil, so avoid low spots. A palm fertiliser can be used, although cycad roots fix nitrogen.

Outdoor and in-ground cultivation

UF/IFAS describes it as an accent plant for tropical gardens in Florida, doing very well in USDA zones 9 to 11. In California, Ganna Walska Lotusland and several Los Angeles and San Diego gardens declare it to BGCI, without saying whether their plants are outdoors. In a Mediterranean climate, a sheltered, lightly shaded spot in well-drained soil, with protection ready for the coldest nights, is the safest choice.

Container cultivation

Its small trunk and modest number of leaves make it a good container plant, as UF/IFAS also notes. Use a gritty, free-draining compost, water regularly in the growing season and sparingly in winter, and bring the pot under cover where frosts are hard.

In cultivation in the UK, US and Australia

It is one of the most widely held Ceratozamia: 66 gardens worldwide declare it to BGCI PlantSearch (queried on 30 October 2026). In the United Kingdom, these are the Royal Botanic Gardens, Kew, the Royal Botanic Garden Edinburgh, Glasgow Botanic Gardens, Birmingham Botanical Gardens, the National Botanic Garden of Wales and Paignton Zoo. In the United States, 38 gardens list it, among them Montgomery Botanical Center (Coral Gables, Florida; 15 accessions in its online catalogue), Fairchild Tropical Botanic Garden, Naples Botanical Garden, the Huntington, Lotusland, San Diego Botanic Garden, the Missouri Botanical Garden, the New York Botanical Garden and the United States Botanic Garden. In Australia, the Royal Botanic Garden Sydney, Royal Botanic Gardens Victoria (Melbourne), the Cairns Botanic Gardens, the Botanic Garden of Adelaide, James Cook University in Townsville and the Hunter Region Botanic Gardens declare it. A BGCI listing shows that a garden has declared the species at some point, not whether the plant is under glass or outdoors.

Propagation

Like all Ceratozamia, it has separate male and female plants and is mostly raised from fresh seed after pollination, usually done by hand in cultivation. UF/IFAS also mentions division of the underground offsets. Clean the seeds wearing gloves and sow them warm in a free-draining mix.

Pests and diseases

UF/IFAS describes it as virtually pest-free and unaffected by the Asian cycad scale (Aulacaspis yasumatsui), a serious pest of cycads in Florida. As with all cycads, the main risk is trunk and root rot in cold, waterlogged soil.

Cold hardiness

Ceratozamia hildae has a reputation as one of the hardier Ceratozamia, but published data are few. UF/IFAS states that it can survive temperatures as low as about −9 °C (15 °F) and does very well in USDA zones 9 to 11, while preferring warm, humid climates.

Mediterranean and European experience

A grower in Pedara (Catania, Sicily, Italy), on the southern slopes of Mount Etna, reports on the Tropicamente forum that his Ceratozamia hildae, planted in the ground and partly protected, came through 18 February 2008 fairly well, when the temperature fell to −5 °C (23 °F), followed by −3 °C (26.6 °F) the next night. No outdoor result has been published in France, and the Jardin zoologique tropical in La Londe-les-Maures (Var, on the French Riviera) has published no observation of it.

United Kingdom, United States and Australia

The UF/IFAS figure is the only published reference for North America; no dated record from a named place is documented. In the UK it is a plant for a cool or heated glasshouse. In the tropical north of Australia, around Cairns and Townsville, where gardens declare it, frost is not a concern.

Toxicity and precautions

No toxicity study specific to Ceratozamia hildae has been published. The risk is documented in other cycads: their seeds and leaves contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a compound harmful to the liver and nervous system. UF/IFAS recalls that all parts of cycads are toxic and potentially fatal to small animals. 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. Its only documented use is ornamental.

Frequently asked questions

Why is it called the bamboo cycad?

Because of its leaves. Its thin leaflets, grouped in small clusters along a slender axis, recall bamboo foliage; it is the only Ceratozamia with this feature.

Is Ceratozamia hildae cold-hardy?

Moderately. The University of Florida gives survival down to about −9 °C (15 °F) and rates it for USDA zones 9 to 11; a partly protected plant in the ground took −5 °C (23 °F) in Sicily. Outside mild areas it needs winter protection.

Does it grow fast?

Yes, for a cycad. According to UF/IFAS it can reach maturity in two to four years in good conditions.

Sun or shade?

Partial shade is best. It accepts moderate sun or deep shade, and the length of its leaves changes with the light it receives.

Is it endangered in the wild?

Yes. It is assessed as Critically Endangered by the IUCN (2022) and lives only in the Sierra Gorda, between San Luis Potosí and Querétaro.

Can it be bought freely?

Not without documents. Like the whole genus, it is listed in CITES Appendix I and Annex A of the EU regulation, seeds included; only plants raised in cultivation, with paperwork, can be traded.

Is it toxic to dogs and cats?

It should be assumed so. No analysis exists for the species, but all cycads are considered toxic, especially their seeds, and can be fatal to small animals.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Landry, G.P. & Wilson, M.C. (1979). A new species of Ceratozamia (Cycadaceae) from San Luis Potosí. Brittonia 31(3): 422–424. https://doi.org/10.2307/2806139 [Original description. Primary source.]
  • Vovides, A.P. & Rees, J.D. (1983). Ceratozamia microstrobila (Zamiaceae), a new species from San Luis Potosí, Mexico. Madroño 30(1): 39–42. [Key separating the small eastern species.]
  • 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 names; open access.]
  • Bösenberg, J.D., Nicolalde-Morejón, F. & Martínez-Domínguez, L. (2022). Ceratozamia hildae. The IUCN Red List of Threatened Species 2022: e.T42124A69864219. https://doi.org/10.2305/IUCN.UK.2022-1.RLTS.T42124A69864219.en [Red List assessment; category confirmed by GBIF.]
  • 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.]