Zamia decumbens

Zamia decumbens is a cycad endemic to the Maya Mountains of Belize, whose largest populations grow at the bottom of limestone sinkholes. This species of the genus Zamia takes its name from the Latin decumbens, “lying down”, because the stems of old plants creep along the ground with their tip turned up instead of growing upright, a rare habit in the genus. For years nurseries and botanists wrongly called it Zamia prasina, until it was described as a separate species in 2009. In English it is known as the “sinkhole cycad”, and it is rated Endangered by the IUCN.

Key facts about Zamia decumbens

  • Accepted name: Zamia decumbens Calonje, Meerman, M.P.Griff. & Hoese (2009), accepted by The World List of Cycads (version 2026.08.15) and by GBIF; POWO could not be consulted directly
  • Former names and synonyms: no synonym; wrongly called Zamia prasina in horticulture and in several publications before 2009
  • Family: Zamiaceae, order Cycadales
  • Common names: “sinkhole cycad”; “corn palm”, the name used by a Belizean naturalist guide according to the original description
  • Natural range: Belize (Cayo, Stann Creek and Toledo districts), Maya Mountains, between 150 and 700 m
  • IUCN status: Endangered (EN), criteria B1ab(v)+2ab(v); C2a(i), assessment published in 2022
  • CITES and other protection: CITES Appendix II (whole genus, since 1977; seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: no measured data; temperatures in its range vary from 16 to 31 °C (60.8 to 87.8 °F) (see Cold hardiness)
  • Light and soil: in the wild, sinkhole floors and rocky ridges, mostly on limestone, in evergreen tropical forest; in sinkholes, in the shade of the walls
  • Habit and adult size: creeping stems up to 80 cm long and 6.7 to 11 cm across; 5 to 17 leaves 90 to 175 cm long
  • In the UK, US and Australia: Montgomery Botanical Center (Florida) lists 27 accession numbers from 2001 to 2014; also listed by Fairchild Tropical Botanic Garden and declared to BGCI by Naples Botanical Garden (Florida); no British or Australian record
  • Toxicity: no data specific to the species; treat it as poisonous, like all cycads (see Toxicity and precautions)

How to recognise Zamia decumbens

The stem is the first clue: in old plants it lies down and runs along the ground, often rots at the base and puts out new roots along its length. The second is the very long stalk of the male cones, which makes them lean outwards. Contrary to what is sometimes said, the leaflets are not leathery but papery. The measurements below come from the original description (Calonje, Meerman, Griffith and Hoese, 2009):

  • Stem: globose to cylindrical, up to 80 cm long and 6.7 to 11 cm in diameter, decumbent and sometimes branched in old plants.
  • Leaves: 5 to 17 per crown, erect or arching, 90 to 175 cm long, light green when they emerge, then dark green. The petiole, 30 to 55 cm long, has an abruptly swollen base (2.2 to 3.2 cm) and moderate to dense prickles up to 5.3 mm long; the rachis, 60 to 120 cm long, is unarmed or has a few prickles in its lower third.
  • Leaflets: up to 28 pairs per leaf, 17.5 to 29 cm long and 2.8 to 4.1 cm wide, papery, lanceolate, gradually tapering to the tip, with a clear lengthwise fold; margin entire or with a few small teeth near the tip. Seedling leaves usually have a single pair of ovate leaflets.
  • Male cones: conical to cylindrical, cream to brown, 10 to 16.5 cm long and 2.1 to 2.5 cm across, single or in groups of two to six or more, on a stalk 12 to 23 cm long that gradually bends to the horizontal; 12 to 18 pollen sacs per scale, in two separate groups.
  • Female cone: single, cylindrical, erect when mature, 12 to 20 cm long and 5.7 to 6.4 cm across; covered with cream down when it emerges, light to dark green when mature; stalk 7 to 13 cm long.
  • Seeds: ovoid to ovoid-pyramidal, red when ripe, 1.7 to 2 cm long.

Hybrids

No hybrid has been documented. The authors saw Zamia decumbens growing with Zamia variegata at one locality in southern Toledo District, with no sign of hybridisation.

Possible confusion

The most persistent confusion concerned its name. After the type of Zamia prasina, described by Bull in 1881, was rediscovered in the Kew herbarium, the sinkhole plants were attributed to that species, and the name “Zamia prasina” circulated in horticulture and in several publications. In 2008 an expedition from Montgomery Botanical Center showed that the leaflets of the sinkhole plants (papery, folded lengthwise, almost entire) had nothing in common with those of the type of Zamia prasina (leathery, strongly toothed, not folded): Zamia prasina is in fact the oldest valid name for the species formerly called Zamia polymorpha, and the sinkhole plants were a new species. Jay Vannini, a naturalist who has grown Central American cycads in the United States and Guatemala, adds that the plant had also been confused with Zamia tuerckheimii by Standley and Steyermark in 1958 (Vannini, 2019).

Among its relatives, the original description compares it with:

  • Zamia tuerckheimii, from Guatemala, considered its closest relative: upright or leaning stems up to 3 m, broader leaflets (usually 4 to 9 cm), petiole unarmed or sparsely prickly, male cones on stalks no longer than 6.5 cm;
  • the Honduran species published as Zamia bussellii and as Zamia onan-reyesii (the priority between the two names was then under discussion): upright stems up to 2 m, papery and clearly toothed leaflets, larger cones;
  • Zamia monticola, described from a single cultivated male plant, which seems to have an upright stem 14 cm across.

In Belize, Ceratozamia robusta occurs throughout the range of Zamia decumbens, and the two species have been seen together at one locality in northern Cayo District.

Taxonomy

Zamia decumbens is an accepted name according to The World List of Cycads and GBIF; POWO could not be consulted directly. The species was described in 2009 by Michael Calonje, Jan Meerman, M. Patrick Griffith and Geoffrey Hoese in the Journal of the Botanical Research Institute of Texas (volume 3, issue 1, pages 31 to 41). The holotype was collected on 2 September 2008 at the bottom of a sinkhole in Toledo District, between 350 and 400 m (Calonje, Meerman and Griffith BZ08-201); it is kept at the Belize herbarium (BRH), with isotypes at FTG, MO, NY and XAL. In the same issue, Calonje and Meerman clarified the identity of Zamia prasina.

According to the original description, its closest relative is Zamia tuerckheimii. Vannini (2019) goes further: he notes that the two share many characters, differing mainly in the length of the male cone stalks and in details of the male scales, that their known populations are only about 48 km (30 miles) apart on similar karst, and that Zamia decumbens might warrant review as a subspecies of Zamia tuerckheimii. This is the opinion of one author; no such change has been published, and The World List of Cycads accepts both species.

The transcriptome study of Lindstrom and colleagues (2024) included a sample from Cayo District, but its text does not discuss the position of the species. It describes a distinct group of seven described species from Honduras, eastern Guatemala and western Belize, adapted to habitats as varied as wet cloud forest, dry deciduous forest and cliffs, without naming them all.

Etymology and history

The epithet comes from the Latin decumbens, “lying on the ground with the tip turned up”, in reference to the habit of old stems (Haynes, 2022, cited by The World List of Cycads).

The story begins in December 1997: two researchers studying wild nutmegs were taken by a naturalist guide to the bottom of a large sinkhole in the Maya Mountains to see plants he called “corn palms”. There they found an ancient Maya kiln, many potsherds and a dense population of a Zamia that matched no species then known from Belize. The 2008 expedition of Montgomery Botanical Center then made its description possible. The World List of Cycads holds photographs taken in the wild in 2008, 2010 and 2014.

Common names

In English the species is called the “sinkhole cycad”, the name used by Griffith and colleagues (2017) in a peer-reviewed study and by Vannini (2019). According to the original description, the guide who led the first researchers to the sinkhole called these plants “corn palms”, a name Vannini also gives. No Spanish name is attested.

In the wild

Zamia decumbens is known from several localities in the Maya Mountains, in the Toledo, Cayo and Stann Creek districts, between 150 and 700 m, in various forms of lowland evergreen tropical forest, on several geological formations, mostly Upper Cretaceous limestones. Some populations lie close to the Guatemalan border, and the authors considered its presence in Petén likely; Vannini (2019) also thinks it probably occurs in eastern Guatemala.

The authors observed seven populations over an area of about 2,600 km², all very small and confined to rocky ridges and summits or to sinkhole floors. The largest occupy two sinkholes in Toledo District, 50 to 80 m across and 30 to 60 m deep, each with about 150 large, reproductive plants; the ridge populations hold 20 plants at most, and much smaller ones. According to the authors, the limiting factor seems to be soil moisture: in the sinkholes, the plants grow against the walls, under the overhang, where light is lower and rain does not hit them directly.

The climate of its range is estimated at 1,800 to 2,800 mm of rain a year, with a dry season from February to May; temperatures range from 16 to 31 °C (60.8 to 87.8 °F), with an annual mean of 22 to 25 °C (71.6 to 77 °F), January being the coolest month and May the warmest. Many weevils of an unidentified Rhopalotria species and beetles of a Pharaxonotha species, two genera regarded as pollinators of Zamia, have been found in the male cones.

A population genetics study published in 2025 (Calonje and colleagues, Plant Species Biology) sampled four populations with ten microsatellite markers: three in dolines (one at a cave entrance and two at the bottom of sinkholes) and one on a rocky hilltop. According to its abstract, genetic variation reflects the karstic history of the limestone rather than geography or habitat type; present-day gene flow between populations is low, the cave population acting as the main source of migrants; the two sinkhole populations were founded first; the doline populations show signs of recent bottlenecks, and the hilltop population a high level of inbreeding, possibly the result of recent illegal collecting.

Conservation status and regulation

Zamia decumbens is rated Endangered (EN) on the IUCN Red List, under criteria B1ab(v)+2ab(v); C2a(i), in the assessment by M. Patrick Griffith and Michael Calonje published in 2022 (The World List of Cycads; GBIF gives the same category; the Red List itself could not be consulted). The authors of the description counted fewer than 350 plants, over an area of occupancy of less than one square kilometre. According to local people, plants were taken for the trade in the past, and seeds still are; in the sinkholes, the authors found signs that female cones had been removed and very few seedlings and juveniles, perhaps because of this continued harvesting. Precise localities have not been published.

Like all Zamia except Zamia restrepoi, Zamia decumbens falls under CITES Appendix II, where the genus has been listed since 4 February 1977. International trade in the plants requires an export permit. The listing carries annotation #4: seeds, pollen, seedlings and tissue cultures obtained in vitro and transported in sterile containers are not covered by CITES. In the European Union the species falls under Annex B of Regulation (EC) No 338/97, whose current list is set by Regulation (EU) 2026/1383, applicable since 29 June 2026.

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 seed in cultivation.

Growing Zamia decumbens

Before 2009 the species circulated in the trade under the wrong name of Zamia prasina. Since its description it has been introduced into the ex situ conservation collections of Montgomery Botanical Center, at Coral Gables in Florida, and of other botanical gardens around the world. A 2022 article in Curtis’s Botanical Magazine illustrates it from field observations and from these cultivated plants and discusses its cultivation at Montgomery; only its summary has been read. Vannini (2019) notes that it has been in limited cultivation for some time, apparently mostly in southern Florida.

Simon Lavaud, of the French specialist nursery Cycadales.eu, does not class it with the other Zamia of Belize and Guatemala, which tolerate a dry winter, but with the lowland forest species of Central and South America, a group he rates “difficult” outside the tropics (Lavaud, 2023). For that group he recommends:

  • a free-draining compost and water that are neutral to acid;
  • night temperatures around 22 °C (71.6 °F), with only brief spells at about 15 °C (59 °F) tolerated;
  • day temperatures of 28 to 30 °C (82.4 to 86 °F); most species tolerate 34 to 35 °C (93.2 to 95 °F), but heat peaks can damage new leaves;
  • high air humidity, between 70 and 90 per cent;
  • in Europe, a glasshouse, conservatory, bright heated room or growth chamber.

The habitat described by the authors adds a few pointers: shade from the sinkhole walls, a moist soil sheltered from direct rain, and limestone. Note that limestone sits oddly with the “neutral to acid” advice given for the group as a whole; the sources do not settle this point. These are recommendations for a group of species and observations of the wild habitat, not results of growing trials.

Outdoor and in-ground cultivation

No outdoor trial has been documented outside the tropics, and the sources read do not say whether the plants in Florida collections are grown outdoors or under cover. The creeping habit of old stems needs room to spread sideways.

Container cultivation

No container-growing report has been published. A wide rather than deep pot suits the creeping stems; a mineral, free-draining compost, warmth all year, high humidity and shade follow the advice above. In cool climates this means a heated glasshouse.

In cultivation in the UK, US and Australia

In short: well represented in Florida collections; no British or Australian record.

  • United States: Montgomery Botanical Center (Coral Gables, Florida) lists 27 accession numbers in its online catalogue: seven from 2001, six from 2008, seven from 2010 and seven from 2014; with 27 numbers, it is one of the best-represented species in its Zamia collection. Fairchild Tropical Botanic Garden (Coral Gables) lists it in its online catalogue (Garden Explorer, updated on 16 October 2026). Montgomery, Fairchild and Naples Botanical Garden (Florida) declare it to BGCI (queried on 25 October 2026). Griffith and colleagues (2017) compared the ex situ plants with the wild populations using ten microsatellite markers and found that the collections faithfully reflect their source populations.
  • United Kingdom: no record in BGCI or in the online catalogues of British gardens (Edinburgh, Cambridge, Chelsea Physic Garden).
  • Australia: no record in BGCI or in the online catalogues of Australian gardens.

Outside these countries, BGCI also lists the Francisco Javier Clavijero botanic garden in Xalapa (Mexico) and the Prague Botanical Garden. A BGCI declaration shows that a garden held the plant at some point, not that it is alive today.

Propagation

No cultivation data have been published beyond the ex situ work at Montgomery. Like all Zamia, the species has separate male and female plants: both are needed to obtain seed, and in cultivation hand pollination is usually necessary. For a species threatened by seed collecting in the wild, propagation in cultivation is of real value for its conservation. Seeds are exempt from CITES under annotation #4, but they must come from plants of legal origin.

Pests and diseases

No pest or disease has been documented in cultivation. In the wild, according to the original description, old stems often rot at the base and put out new roots along their creeping part. Scale insects are, as in all cycads, the commonest pest in cultivation.

Cold hardiness

No measured data on cold tolerance exist for Zamia decumbens. In its range, temperatures vary from 16 to 31 °C (60.8 to 87.8 °F) according to the climatic data cited by the original description: nothing suggests exposure to frost, and no threshold can be proposed.

Mediterranean and European experience

No growing result has been published in France or elsewhere in Europe, in the ground or in a pot, and no dated frost episode concerns the species. Lavaud (2023), who lives in Montpellier, in southern France, explains that even in July and August the nights there, around 19 °C (66.2 °F), are cooler than lowland tropical Zamia need, and the air much drier. Under a Mediterranean climate, as in the UK, it is a plant for a heated glasshouse.

United Kingdom, United States and Australia

No dated cold record has been published. The plants in Florida collections are grown in a climate without significant frost, and the sources read say nothing about their behaviour in cold spells.

Toxicity and precautions

No toxicity study specific to Zamia decumbens has been published. The risk is, however, documented in the genus and in other cycads: Zamia contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, and for Zamia furfuracea the ASPCA cites cycasin and BMAA, a neurotoxic amino acid, with vomiting, bloody diarrhoea and liver damage in dogs, cats and horses; the seeds are the most dangerous part. In the absence of evidence to the contrary, treat the plant as poisonous: keep seeds and leaves out of reach of children and animals, and wear gloves to clean seeds. If any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

No traditional use specific to the species has been documented. The Maya kiln and the potsherds found at the bottom of the first sinkhole explored say nothing about any use of the plant, and the name “corn palm” given by the guide is not explained in the sources.

Frequently asked questions

Why is it called “decumbens”?

From the Latin decumbens, “lying down with the tip turned up”: the stems of old plants creep along the ground instead of growing upright.

Where does it grow?

Only in Belize, in the Maya Mountains (Toledo, Cayo and Stann Creek districts), between 150 and 700 m, mostly at the bottom of limestone sinkholes; it may also occur just across the border in Guatemala.

What is its connection with Zamia prasina?

None, apart from a naming error: for years the sinkhole plants were sold and published as Zamia prasina. In 2009 it was shown that Zamia prasina is the valid name of the species once called Zamia polymorpha, and that the sinkhole plants were a new species.

What is its closest relative?

According to the original description, Zamia tuerckheimii of Guatemala, which nevertheless has upright stems up to 3 m and broader leaflets. One author has even suggested treating Zamia decumbens as a subspecies of it, but this has not been published.

Is it endangered?

Yes. The IUCN rates it Endangered: fewer than 350 plants were counted in 2009, its populations are small and seeds are still collected for the trade.

How much cold can it take?

Nobody knows: no measured data exist. Its range has temperatures of 16 to 31 °C (60.8 to 87.8 °F); in the UK, it needs a heated glasshouse.

Is it poisonous?

It should be assumed so. No analysis has been made of this species, but the cycads studied contain serious toxins, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • 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. [Protologue; full text read.]
  • Calonje, M. & Meerman, J. (2009). What is Zamia prasina (Zamiaceae: Cycadales)? Journal of the Botanical Research Institute of Texas 3(1): 43–49. [Nomenclatural clarification; cited by the protologue, not consulted.]
  • Griffith, M.P., Calonje, M., Meerow, A.W., Francisco-Ortega, J., Knowles, L., Aguilar, R., Tut, F., Sánchez, V., Meyer, A., Noblick, L.R. & Magellan, T.M. (2017). Will the same ex situ protocols give similar results for closely related species? Biodiversity and Conservation 26(12): 2951–2966. https://doi.org/10.1007/s10531-017-1400-2 [Comparison of wild and ex situ plants with microsatellites; abstract read.]
  • Herrera-Blitman, J., Calonje, M., Meerman, J., Aguilar, J., Meerow, A.W., Francisco-Ortega, J. & Griffith, M.P. (2022). Zamia decumbens: Cycadales, Zamiaceae. Curtis’s Botanical Magazine 39: 517–539. https://doi.org/10.1111/curt.12459 [Illustration and cultivation in the ex situ collections of Montgomery Botanical Center; summary read.]
  • Calonje, M., Meerow, A.W., Meerman, J. et al. (2025). Population genetics of Zamia decumbens (Zamiaceae, Cycadales), an endangered cycad from the Maya Mountains of Belize. Plant Species Biology 40(4): 324–340. https://doi.org/10.1111/1442-1984.12473 [Population genetics; abstract read.]
  • Lindstrom, A., Habib, S., Dong, S., Gong, Y., Liu, J., Calonje, M., Stevenson, D. & Zhang, S. (2024). Transcriptome sequencing data provide a solid base to understand the phylogenetic relationships, biogeography and reticulated evolution of the genus Zamia L. (Cycadales: Zamiaceae). Annals of Botany 134(5): 747–768. https://doi.org/10.1093/aob/mcae065 [Sample from Cayo; position of the species not discussed in the text; full text consulted.]
  • Lavaud, S. (2023). Comment cultiver les Zamia en climat tempéré. Cycadales.eu. [Growing advice for groups of species; read directly.]
  • Vannini, J. (2019). Central American and Panamanian cycads in field and greenhouse. Exotica Esoterica, 17 February 2019. [Online article by a naturalist and collector; read.]
  • Griffith, M.P. & Calonje, M. (2022). Zamia decumbens. The IUCN Red List of Threatened Species 2022. [Current assessment (EN); Red List page not consulted (access blocked), status taken from The World List of Cycads.]
  • 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; not consulted directly.]
  • 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; consulted directly.]