The genus Zamia

Zamia L. is the most diverse cycad genus in the New World — approximately 80 species ranging from Florida and the Caribbean through Mexico, Central America and into South America as far south as Bolivia. It is also the most morphologically and ecologically diverse cycad genus on Earth: from tiny, stemless understorey herbs barely 20 cm tall to large landscape plants with visible trunks, and from dry coastal scrub to tropical rainforest canopy, including the only truly epiphytic cycad species known (Zamia pseudoparasitica). For gardeners, Zamia offers compact, shade-tolerant, low-maintenance cycads ideal for understorey plantings, containers and tropical gardens.

Taxonomy and systematic position

Family Zamiaceae, order Cycadales. The genus was described by Linnaeus in 1763, with Zamia pumila (the coontie) as the type species. The most influential modern revision is that of Stevenson (2001–2012) and collaborators. The World List of Cycads recognises approximately 80 species. The formerly distinct genus Chigua (two species from Colombia with distinctive emergent roots) has been sunk into Zamia following molecular phylogenetic studies (Griffith et al. 2012).

Geographic range and diversity

The genus ranges from Florida (the southernmost native cycad population in the continental United States — Zamia integrifolia) through the Caribbean (Cuba, Jamaica, Bahamas, Puerto Rico), Mexico, Central America (Guatemala, Belize, Honduras, Nicaragua, Costa Rica, Panama), and South America (Colombia, Venezuela, Ecuador, Peru, Bolivia, Brazil). The centre of diversity is Panama and Colombia, where the greatest concentration of species occurs.

Ecological diversity

No other cycad genus occupies such a wide range of niches:

  • Understorey of tropical rainforest — the majority of species; small, shade-tolerant, often with subterranean stems.
  • Coastal scrub and sand dunes — Zamia integrifolia (Florida), Zamia pumila (Caribbean).
  • Epiphytic — Zamia pseudoparasitica, the only known epiphytic cycad, growing on tree trunks and branches in Panamanian cloud forests.
  • Montane cloud forests — Zamia disodon, Zamia montana.
  • Tropical dry forests — Zamia furfuracea (Mexico), Zamia loddigesii.

Conservation and threats

IUCN status

Many Zamia species are threatened by habitat destruction — particularly deforestation in Central America and Colombia. Zamia lucayana (Bahamas) is Critically Endangered with fewer than 2,500 individuals. Zamia encephalartoides (Colombia) faces severe pressure from agricultural expansion. In Florida, Zamia integrifolia is a protected species with a long ethnobotanical history (the coontie was a major starch source for the Seminole and Calusa peoples).

CITES

All Zamia species are listed under CITES Appendix II, requiring export permits for international trade. This is a less restrictive listing than for Encephalartos (Appendix I), reflecting the generally larger wild populations and more extensive cultivation of most Zamia species.

Cultivation

Light

Most Zamia species are shade-tolerant to shade-preferring — a major difference from most other cycad genera. This reflects their predominantly forest-understorey ecology. Bright, filtered light or dappled shade is ideal for the majority. A few species from open habitats (Zamia integrifolia, Zamia furfuracea) tolerate full sun and are more versatile in landscape use. Direct hot sun can scorch the leaves of forest-dwelling species.

Temperature and cold hardiness

Zamia is predominantly a tropical genus, and most species are frost-tender:

  • Hardiest (−5 to −8 °C, USDA zone 8b–9a): Zamia integrifolia (Florida coontie — the hardiest Zamia, surviving brief freezes in northern Florida), Zamia pumila.
  • Semi-hardy (−2 to −4 °C, USDA zone 9b–10a): Zamia furfuracea (cardboard palm — widely cultivated and fairly cold-tolerant).
  • Tender (above 0 °C): most South American and Central American species. These are greenhouse or indoor plants in temperate climates.

Substrate

Well-drained but more organically rich than for desert-adapted cycads. Zamia species grow in forest soils with significant organic content. A mix of 40–50% mineral material (perlite, pumice, coarse sand) and 50–60% organic material (composted bark, coco coir, leaf mould) works well for most species. Soil pH: slightly acidic to neutral for most forest species.

Watering

More moisture-tolerant than Cycas or Encephalartos, but drainage remains essential. Water regularly during the growing season; reduce in winter. Forest species tolerate higher ambient humidity than arid-climate cycads.

Propagation

Pollination

Dioecious. Hand pollination as for other cycad genera. Zamia pollination in the wild often involves curculionid beetles (weevils) and the thermogenic push-pull mechanism documented by Terry et al. (2007). Male cones are typically elongated and cylindrical; female cones are shorter and ovoid.

Seed preparation and sowing

Seeds are typically bright red or orange when mature. Remove the sarcotesta completely (wear gloves). Soak in warm water for 24–48 hours. Sow half-buried in a well-drained mix of perlite or coarse sand. Temperature: 25–30 °C. Most Zamia species germinate in 4–8 weeks — some of the fastest germination in the cycad world. Zamia integrifolia (coontie) germinates readily within about six weeks when sown under a thin layer of soil.

Raising seedlings

Provide filtered light (not direct hot sun for forest species), warmth and regular moisture. Seedling growth is moderate by cycad standards — faster than Encephalartos but still slow by angiosperm standards. Feed with a balanced, slow-release fertiliser. Most species develop a visible caudex within 2–3 years.

Vegetative propagation

Some species produce basal offsets or branching caudices that can be divided. Zamia furfuracea suckers moderately; Zamia integrifolia produces multi-stemmed clumps that can be divided.

Pests and diseases

Cycad aulacaspis scale (Aulacaspis yasumatsui) — a serious threat, particularly for Zamia species grown alongside infested Cycas. The coontie populations of Florida were severely impacted after the scale’s arrival in 1996. Treat with systemic insecticides.

Atala butterfly (Eumaeus atala) — larvae feed on Zamia integrifolia leaves in Florida. A beautiful but potentially damaging pest. The atala was itself once considered near-extinct due to loss of its coontie host plant, making the relationship a conservation paradox: both the butterfly and the cycad are threatened.

Mealybugs and scale insects — common on pot-grown plants. Standard treatments.

Root rot — in waterlogged conditions. Prevention: drainage.

Species of Zamia

Approximately 80 species. Arranged by broad geographic region. Only the most important or distinctive species are annotated; the complete list is available from the World List of Cycads.

North America (United States)

  • Zamia integrifolia — Florida coontie; the only cycad native to the continental United States (Florida & Georgia) ; USDA zone 8b

Caribbean

  • Zamia pumila — the type species; Cuba, Jamaica, Bahamas, Cayman Islands, Puerto Rico
  • Zamia lucayana — Bahamas; Critically Endangered
  • Zamia pygmaea — Cuba; one of the smallest cycads
  • Zamia angustifolia — Cuba, Bahamas
  • Zamia erosa — Jamaica
  • Zamia amblyphyllidia — Puerto Rico

Mexico and Central America

  • Zamia furfuracea — cardboard palm; Veracruz, Mexico; widely cultivated; hardy to −2/−4 °C
  • Zamia loddigesii — Mexico; widespread
  • Zamia vazquezii — Veracruz, Mexico; Critically Endangered
  • Zamia katzeriana — Costa Rica
  • Zamia neurophyllidia — Costa Rica, Panama
  • Zamia pseudoparasitica — Panama; the only epiphytic cycad; grows on tree trunks in cloud forest
  • Zamia skinneri — Costa Rica, Panama
  • Zamia standleyi — Honduras, Guatemala
  • Zamia imperialis — Coclé Province, Panama
  • Zamia herrerae — Guatemala, Mexico
  • Zamia purpurea — Oaxaca, Mexico
  • Zamia soconuscensis — Chiapas, Mexico
  • Zamia spartea — Oaxaca, Mexico

South America

Authority websites and online databases

World List of Cycads
https://www.cycadlist.org/

Montgomery Botanical Center
A leading institution for Zamia research and conservation, with one of the most comprehensive living collections.
https://www.montgomerybotanical.org/

Fairchild Tropical Botanic Garden
Major cycad research and conservation programme, particularly for New World species.
https://fairchildgarden.org/

IUCN SSC Cycad Specialist Group
https://www.cycadgroup.org/

The IUCN Red List of Threatened Species
https://www.iucnredlist.org/

Plants of the World Online (POWO)
https://powo.science.kew.org/

Bibliography

Griffith, M.P., Calonje, M., Stevenson, D.W., Husby, C.E. & Little, D.P. — “Time, place, and relationships among threatened cycads.” Proceedings of the Royal Society B 279 (2012): 2250–2258. Molecular phylogenetics of Zamia with biogeographic and conservation implications.

Jones, D.L. — Cycads of the World. 2nd edition, 2002.

Whitelock, L.M. — The Cycads. Timber Press, 2002.

Calonje, M., Stevenson, D.W. & Stanberg, L. — The World List of Cycads (online). https://www.cycadlist.org/.

Dehgan, B. & Johnson, C.R. — “Improved seed germination of Zamia floridana with H₂SO₄ and GA₃.” Scientia Horticulturae 19 (1983): 37–43.

Terry, I. et al. — “Odor-mediated push-pull pollination in cycads.” Science 318 (2007): 70.

Donaldson, J.S. (ed.) — Cycads: Status Survey and Conservation Action Plan. IUCN, 2003.