Zamia melanorrhachis

Zamia melanorrhachis is a small cycad of northern Colombia, known from the departments of Antioquia, Bolívar, Córdoba and Santander, where it grows in lowland forest between about 30 and 500 m. Described in 2001, this species of the genus Zamia is recognised by its very dark, purple to almost black petiole and rachis, which give it its name, and by its tiny male cones carried at the tip of stalks up to 50 cm long. The IUCN rates it Endangered (2022 assessment).

Key facts about Zamia melanorrhachis

  • Accepted name: Zamia melanorrhachis D.W.Stev. (2001), accepted by The World List of Cycads (version 2026.08.15), by GBIF and by the World Checklist of Vascular Plants, on which POWO is based; POWO could not be consulted directly
  • Former names and synonyms: none
  • Family: Zamiaceae, order Cycadales
  • Common names: no English name; “corocito” and “(Mui) ibaracú” according to the original description, without language or region
  • Natural range: Colombia (Antioquia, Bolívar, Córdoba, Santander); specimens collected between 30 and 500 m
  • IUCN status: Endangered (EN B2ab(iii,v)), 2022 assessment
  • 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 cold record; a lowland tropical plant (see Cold hardiness)
  • Light and soil: lowland forest; light and soil not described in the literature
  • Habit and adult size: underground, tuberous stem 5 to 8 cm across; 2 to 5 erect leaves up to 50 cm long
  • In the UK, US and Australia: declared by the University of California Botanical Garden at Berkeley and the botanical garden of the University of Hawaii at Hilo; none recorded in the UK or Australia
  • Toxicity: no data specific to the species; treat it as poisonous, like all cycads (see Toxicity and precautions); a herbarium label reports that the tubers are eaten (see Traditional uses)

How to recognise Zamia melanorrhachis

It is a small Zamia with a dark leaf stalk and minute male cones on very long stalks. The original description, written in Spanish with a Latin diagnosis by Dennis Stevenson for the Flora de Colombia (2001), gives the following characters:

  • Stem: underground and tuberous, 5 to 8 cm in diameter; cataphylls with a triangular base and a linear-lanceolate tip, 2 to 5 cm long.
  • Leaves: 2 to 5, erect, oblong, up to 50 cm long; petiole rounded in section, up to 25 cm, dark purple to blackish, armed with very short prickles; rachis 20 to 30 cm, of the same colour, usually with very short prickles on its lower half, carrying 4 to 10 pairs of leaflets.
  • Leaflets: oblong-lanceolate, 12 to 15 cm long and 1 to 2 cm wide, papery, stalkless, with a wedge-shaped base, a pointed tip and a saw-toothed margin on the upper two thirds. The protologue describes them as not grooved; the 2021 key describes them as flat, curved forwards and marked above by a prominent longitudinal fold.
  • Male cones: yellowish to light brown, ovoid, only 1 to 3 cm long and 0.5 to 1 cm across, on a peduncle 30 to 50 cm long; pollen sacs on both faces of the scales, fewer (1 to 3) on the upper face.
  • Female cones: reddish brown, cylindrical to ovoid-cylindrical, 5 to 8 cm long and 3 to 4 cm across.
  • Seeds: red, 1 to 1.5 cm long and 5 to 8 mm in diameter.

Hybrids

No hybrid, natural or raised in cultivation, is documented.

Possible confusion

Zamia melanorrhachis belongs to the Zamia manicata clade, a group of species from northern Colombia whose leaves differ greatly from one another. The key published in 2021 by Michael Calonje and colleagues separates it from its neighbours as follows:

  • Zamia manicata: leaflets carried on a short stalk with a glandular collar;
  • Zamia restrepoi: leaflets with a clearly visible midrib;
  • Zamia disodon: elliptic, membranous leaflets with raised veins;
  • Zamia sinuensis, from Córdoba: strongly undulate, almost symmetrical leaflets without a longitudinal fold;
  • Zamia imbricata: unarmed petiole and leaflets overlapping like roof tiles.

Outside this group, the key to the Colombian Zamia by Calderón and Stevenson (2003) contrasts it with Zamia muricata, which has 15 to 35 pairs of symmetrical leaflets and a green, clearly prickly petiole. The original description also compares it with Zamia hymenophyllidia, from Amazonia, whose petiole and rachis are not dark.

Taxonomy

Zamia melanorrhachis is an accepted name according to The World List of Cycads, GBIF and the World Checklist of Vascular Plants, on which POWO is based (read on GBIF, version of 4 June 2026); POWO itself could not be consulted. It was published in 2001 by Dennis Wm. Stevenson, of the New York Botanical Garden, in the part of the Flora de Colombia devoted to the Cycadales (volume 21, page 55, figure 11). It has never had another name.

Molecular phylogenies have clarified its place in the genus. According to Calonje and colleagues (2021), it belongs to the Zamia manicata clade, a strongly supported group (Calonje et al., 2019) whose members share underground or partly buried stems, strongly toothed leaflets, cones on very long peduncles (usually more than 20 cm), small seeds with a very thin fleshy coat and tiny male cones. The transcriptome phylogeny of Lindstrom and colleagues (2024) did not sample Zamia melanorrhachis, but its authors consider it likely to belong, with Zamia imbricata, to the northern Colombian subgroup that includes Zamia disodon, Zamia manicata, Zamia restrepoi and Zamia sinuensis, on the basis of shared morphological characters.

Its range, on the other hand, has narrowed. The original description extended it from north-western Colombia to the departments of Meta and Amazonas; The World List of Cycads now retains only Antioquia, Bolívar, Córdoba and Santander. One of the Meta specimens cited in 2001 (Callejas and Marulanda 5911) is now among the paratypes of Zamia orinoquiensis, described in 2022. GBIF still lists specimens labelled with this name from Caquetá, Meta, Casanare and Amazonas, outside the range accepted today; their identity has not been revised in a publication.

Etymology and history

The epithet melanorrhachis comes from the Greek melas, “black” or “very dark”, and rhachis, the axis of the leaf: it refers to the dark brown to dark purple rachis (Haynes, 2022, as quoted by The World List of Cycads; the original description says the same).

The type was collected in 1987 in the department of Córdoba, 10 km north of Caucasia on the road to the Río Uré, at about 90 m, by Dennis Stevenson, Jorge Brand and Knut Norstog (number 695), according to the herbarium labels published on GBIF. The holotype is kept at the National Herbarium of Colombia (COL), with isotypes at the University of Antioquia (HUA), the New York Botanical Garden (NY) and Utrecht (U). The description also cites three collections made by O. Haught in Santander, between 100 and 500 m; the label of number 1447, from 1934, places it near Barrancabermeja, in the Magdalena valley.

Common names

No English name is attested. The original description gives the names “corocito” and “(Mui) ibaracú”, without stating the language, the region where they are used or the meaning of the abbreviation “Mui”. Since the range attributed to the species has shrunk since 2001, it is not known whether these names apply to plants still placed in Zamia melanorrhachis today.

In the wild

Zamia melanorrhachis is endemic to northern Colombia, mainly in the Magdalena-Urabá moist forests ecoregion, home to most of the Zamia manicata clade. The specimens cited in the original description were collected between 30 and 500 m. Herbarium labels published on GBIF add a few details: the type at 90 m, plants at 45 to 120 m near Uré (Córdoba) in 1990, a collection in tropical dry forest along the Montería to Planeta Rica road in 1991, another at 110 m in Bolívar in 2010 in a forest recorded as humid to dry tropical, and plants at 215 m in Santander in 2015. In 2021 Calonje and colleagues studied populations at Barrancabermeja and Betulia (Santander) and at Montelíbano (Córdoba). The soil and the phenology have not been described.

Simon Lavaud, of the French specialist nursery Cycadales.eu, gives an idea of the climate in which it grows: temperatures fairly stable all year, with night-time minima of about 24 °C (75 °F) and daytime maxima of 30 °C (86 °F), about 4,600 mm of rain a year and air humidity of 75 to 87 % (Lavaud, 2023). He does not name the locality, to protect the plants.

Two population studies are cited by Calonje and colleagues (2021): a demographic study (López-Gallego, 2007) and a genetic study using microsatellite markers (Aristizábal and colleagues, 2018), which covered populations of the Magdalena valley and found strong signs of genetic isolation between them.

Conservation status and regulation

Zamia melanorrhachis is rated Endangered (EN) by the IUCN under criteria B2ab(iii,v), in an assessment by Cristina López-Gallego published in 2022 (The World List of Cycads; reference checked on Crossref): a small area of occupancy, fragmented populations and a continuing decline in the quality of the habitat and in the number of mature plants. In 2001 Dennis Stevenson noted that the species was known from only four separate localities, adding that recent collections showed it to be commoner than had been thought.

Like all Zamia except Zamia restrepoi, which is in Appendix I, Zamia melanorrhachis is covered by the listing of the genus in CITES Appendix II, in force since 4 February 1977. Annotation #4 (the version adopted at CoP20, in force on 5 March 2026) exempts seeds, pollen, seedlings and tissue cultures obtained in vitro and transported in sterile containers, and cut flowers of artificially propagated plants; international trade in the plants themselves requires an export permit. 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. Species+, the official CITES database, names the species and confirms this status (checked on 3 October 2026).

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

Growing Zamia melanorrhachis

Little has been published about its cultivation. The original description simply says that the species “grows well when cultivated”, and no grower has published detailed advice or results. BGCI lists only three gardens that declare it: the Jardín Botánico de Medellín, in Colombia, and two in the United States.

Simon Lavaud places it in a group he rates difficult, the Zamia of Central America and of the South American lowland forests, whose climates are warm and humid all year. He warns that European climates are generally too cold and too dry for them, even in summer, and that plants then grow weakly and risk root rot. For this group he recommends a glasshouse, a conservatory, a bright heated room or even an indoor growing chamber, with a free-draining compost and water both neutral to acid, nights at about 22 °C (72 °F), which most plants tolerate dropping briefly to about 15 °C (59 °F), days at 28 to 30 °C (82 to 86 °F) and air humidity of 70 to 90 % (Lavaud, 2023). This is advice for the whole group, not the result of a trial with this species.

Outdoor and in-ground cultivation

Outdoors it is a plant only for humid tropical gardens without a cool season. No outdoor planting has been documented outside Colombia.

Container cultivation

Elsewhere it belongs in a heated glasshouse or a warm, bright room. Its small size, with leaves no more than 50 cm long, suggests a plant suited to a pot, but no grower has published a result to confirm it. A free-draining, neutral to acidic compost, constant warmth and high humidity follow from its habitat and from Lavaud’s advice for its group.

In cultivation in the UK, US and Australia

In short: very rare in collections, and absent from British and Australian gardens.

  • United States: the University of California Botanical Garden at Berkeley and the botanical garden of the University of Hawaii at Hilo declare it to BGCI (queried on 25 October 2026); such a declaration does not prove that the plants are still alive, and neither garden has published anything on how they are grown. The online catalogue of Montgomery Botanical Center does not list it.
  • United Kingdom: no record in BGCI or in the online catalogues of British gardens. Trebrown Nurseries, a British nursery, rates it USDA zone 10a; this is a commercial classification, not a measured result.
  • Australia: no record in BGCI.

Propagation

The plant is dioecious: a male and a female plant are needed to obtain seed, and in cultivation hand pollination. No germination data specific to the species have been published. Seeds are exempt from CITES under annotation #4; make sure they come from cultivated plants.

Pests and diseases

No pest or disease specific to the species is documented. In cultivation, Zamia are chiefly at risk from rot in cold, waterlogged compost and from scale insects.

Cold hardiness

No cold-tolerance data exist for Zamia melanorrhachis. It is a plant of lowland tropical forest whose climate, according to Lavaud, keeps night-time minima of about 24 °C (75 °F); nothing suggests that it can take frost, or even a prolonged cool spell.

Mediterranean and European experience

No cultivation result has been published in France or elsewhere in Europe, either in the ground or in a pot, and no dated frost episode concerns the species. For readers in Mediterranean-type climates such as California or southern Australia, it is, on present knowledge, a plant for a heated glasshouse; Lavaud’s comparison between its habitat and the summer climate of Montpellier, where nights are about 19 °C (66 °F) in July and August and the air much drier, shows how far even a warm Mediterranean summer falls short of its needs.

United Kingdom, United States and Australia

No cold record or cultivation report exists from these countries, and neither of the two American gardens that hold it has published how its plants respond to cool weather.

Toxicity and precautions

No toxicity study specific to Zamia melanorrhachis has been published. The risk is, however, well documented in cycads: Zamia contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a compound toxic to the liver and nervous system, and the ASPCA cites cycasin and BMAA, a neurotoxic amino acid, for Zamia furfuracea, which it lists as toxic to dogs, cats and horses; the seeds are the most dangerous part. The edible tubers mentioned on a herbarium label (see Traditional uses) do not show that the plant is harmless: the starch of the Florida coontie, Zamia integrifolia, was eaten only after the toxin had been removed by grinding and washing. 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

The original description reports, from the label of a specimen collected in Amazonas (Londoño and colleagues, number 510), that the tubers are edible. No preparation is described, and this specimen comes from a region that The World List of Cycads no longer includes in the range of the species: the information cannot be attached with certainty to Zamia melanorrhachis as it is understood today.

Frequently asked questions

Where does Zamia melanorrhachis grow?

In northern Colombia only (Antioquia, Bolívar, Córdoba and Santander), in lowland forest; the known specimens come from 30 to 500 m.

Where does the name come from?

From the Greek melas, “black”, and rhachis, the axis of the leaf: its petiole and rachis are dark purple to almost black.

How can it be recognised?

By its small size (leaves no more than 50 cm long), its dark leaf stalk, its 4 to 10 pairs of toothed leaflets curving forwards and its minute male cones, only 1 to 3 cm long, on stalks 30 to 50 cm long.

How does it differ from Zamia muricata?

Mainly by its leaves. Zamia muricata, from Venezuela and the Guajira peninsula, carries 15 to 35 pairs of symmetrical leaflets on a green, clearly prickly petiole; Zamia melanorrhachis has only 4 to 10 pairs, on a dark petiole with very short prickles.

Is it endangered?

Yes. The IUCN rates it Endangered (2022): its populations are small, fragmented and genetically isolated from one another.

Is it easy to grow?

Perhaps, in the right conditions. Its author noted that it grows well in cultivation, but no grower has published advice or results, and the nursery that classifies it places it in a group that is difficult outside the tropics.

Is it hardy?

Almost certainly not. No cold data exist, and it comes from lowland tropical forest where nights stay around 24 °C (75 °F).

Is it poisonous?

It must be assumed so, despite a herbarium label reporting edible tubers. The cycads studied contain serious toxins, mainly in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Stevenson, D.W. (2001). Orden Cycadales. Flora de Colombia 21: 1–91. Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá. [Original description of Zamia melanorrhachis, pp. 55–57; read.]
  • Calderón, E. & Stevenson, D.W. (2003). Una nueva especie del género Zamia L. (Zamiaceae), de los Andes de Colombia y clave actualizada para las especies del género en Colombia. Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales 27(105): 485–490. [Key consulted.]
  • Calonje, M., Castro Hernández, J., Coca, L.F., Jaramillo, D. & Aristizábal, A. (2021). Two new species of Zamia (Zamiaceae, Cycadales) from the Magdalena-Urabá moist forests ecoregion of northern Colombia. Phytotaxa 497(1): 1–19. https://doi.org/10.11646/phytotaxa.497.1.1 [Full text consulted.]
  • 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 [Full text read on PubMed Central.]
  • Aristizábal, A., Tuberquia, D.J. & Sanín, M.J. (2018). Conservation genetics of two highly endangered and poorly known species of Zamia (Zamiaceae: Cycadales) in Colombia. Journal of Heredity 109(4): 438–445. https://doi.org/10.1093/jhered/esx110 [Abstract read on Europe PMC.]
  • López-Gallego, C. (2022). Zamia melanorrhachis. The IUCN Red List of Threatened Species 2022: e.T42136A69838014. https://doi.org/10.2305/IUCN.UK.2022-1.RLTS.T42136A69838014.en [Red List assessment; reference given by The World List of Cycads and checked on Crossref; the Red List page could not be consulted.]
  • Calonje, M., Meerow, A.W., Griffith, M.P., Salas-Leiva, D., Vovides, A.P., Coiro, M. & Francisco-Ortega, J. (2019). A time-calibrated species tree phylogeny of the New World cycad genus Zamia L. (Zamiaceae, Cycadales). International Journal of Plant Sciences 180(4): 286–314. [Not consulted; cited after Calonje and colleagues (2021).]
  • 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; 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.]