Dioon salas-moralesiae

Dioon salas-moralesiae is a cycad from south-eastern Oaxaca, Mexico, described in 2021 from populations previously included in Dioon merolae. This species of the genus Dioon grows west of the Isthmus of Tehuantepec, notably at San Miguel Tenango, its type locality, and at Santiago Lachiguiri. It differs from Dioon merolae, found on the other side of the isthmus, in its broad leaflets, which overlap less and are only slightly curved downwards at the tip. Published as Dioon salas-moralesae, a spelling still common in the literature, it honours the Mexican botanist Silvia H. Salas-Morales. It has not yet been assessed by the IUCN, and nothing has been published on its cultivation.

Key facts about Dioon salas-moralesiae

  • Accepted name: Dioon salas-moralesiae Gut.Ortega & Pérez-Farr. (2021), accepted by The World List of Cycads (version 2026.08.15), IPNI, GBIF and Kew’s World Checklist of Vascular Plants, the database behind POWO (June 2026 version, published on GBIF)
  • Former names and synonyms: published as Dioon salas-moralesae; the populations were formerly included in Dioon merolae
  • Family: Zamiaceae, order Cycadales
  • Common names: none attested, in English or in Spanish
  • Natural range: Mexico, south-eastern Oaxaca, west of the Isthmus of Tehuantepec (San Miguel Tenango, Santiago Lachiguiri)
  • IUCN status: Not Evaluated (NE)
  • CITES and other protection: CITES Appendix II through the listing of all cycads (annotation #4: seeds exempt), without its own record in Species+; Annex B in the European Union; not listed by name in the Mexican standard NOM-059-SEMARNAT-2010 or its 2019 update
  • Documented hardiness: no data
  • Light and soil: not documented
  • Habit and adult size: erect trunk; detailed measurements given in the original description (2021)
  • In the UK, US and Australia: Montgomery Botanical Center (three accessions from 2004) and Naples Botanical Garden (BGCI); no British or Australian garden listed
  • Toxicity: no analysis specific to the species; toxins documented in other cycads (see Toxicity and precautions)

How to recognise Dioon salas-moralesiae

Dioon salas-moralesiae is recognised mainly by its leaflets: broad, slightly overlapping and only slightly curved downwards at the tip. The characters below come from the abstract of the article, its identification key and the captions of its figures, published on Zenodo (Gutiérrez-Ortega and co-authors, 2021):

  • Trunk: erect; the crown of leaves is ascending on the adult plants photographed at the type locality;
  • Leaflets: broad, slightly overlapping and slightly bent downwards in their upper part; they are not inserted obliquely on the rachis;
  • Cones: according to the authors, the colour of the basal scales of the female cone separates the species from its two closest relatives; the captions do not give the colour itself;
  • Seeds: their size differs significantly from that of the neighbouring species, according to a statistical comparison published in the article.

The precise dimensions of the trunk, leaves and cones are given only in the full text of the description.

Hybrids

No hybrid of Dioon salas-moralesiae has been reported.

Possible confusion

The most likely confusion is with Dioon merolae, from which the species was split. According to the 2021 key, Dioon merolae has leaflets strongly curved downwards in their upper part and strongly overlapping, whereas Dioon salas-moralesiae has broad leaflets, only slightly curved and less overlapping. The populations of Dioon merolae photographed by the authors come from Chiapas, east of the Isthmus of Tehuantepec, notably from Tonalá, its type locality.

The second close species is Dioon oaxacensis, from the arid central valleys of Oaxaca, with flat, stiff, straight leaflets and larger cones (Gutiérrez-Ortega and co-authors, 2020b). The key also mentions Dioon califanoi, whose leaflets are inserted obliquely on a strongly keeled rachis. According to the 2021 abstract, Dioon salas-moralesiae resembles Dioon merolae in its qualitative characters, but its measurements often place it between the two species.

In practice, provenance is the surest clue: a plant sold as Dioon merolae without known origin cannot be assigned with certainty to either species.

Taxonomy

Dioon salas-moralesiae is an accepted name. José Said Gutiérrez-Ortega and Miguel Ángel Pérez-Farrera described it in an article co-signed with Jeffrey Chemnick and Timothy J. Gregory, published on 14 December 2021 in Phytotaxa (528(2): 93–110; name published on page 103). The type is a female plant collected on 8 November 2016 at San Miguel Tenango (Oaxaca) by Pérez-Farrera and Gutiérrez-Ortega (number 3466); the holotype is kept at the HEM herbarium, with duplicates at MEXU and XAL.

The epithet was published as salas-moralesae. IPNI and The World List of Cycads correct it to salas-moralesiae, the regular form of an epithet honouring a woman whose name ends in a consonant. Both spellings refer to the same plant, and the original form remains common in publications; BGCI PlantSearch lists it as “salasmoralesiae”.

The split was the outcome of several studies. In 2020, an analysis of chloroplast DNA, markers spread across the whole genome, morphology and climate (Gutiérrez-Ortega and co-authors, 2020a, New Phytologist) showed that Dioon merolae, as then understood, consisted of three lineages separated by areas unsuitable for cycads. One was described the same year as Dioon oaxacensis. The other two lay on either side of the Isthmus of Tehuantepec; in 2021, morphological observations and statistical tests showed that the populations of south-eastern Oaxaca formed a distinct species, Dioon salas-moralesiae. For the grower, this means that a plant from Oaxaca labelled Dioon merolae before 2020 may belong to one of the two newer species.

The species belongs to the Purpusii clade, with Dioon merolae, Dioon oaxacensis, Dioon argenteum, Dioon califanoi, Dioon caputoi, Dioon holmgrenii, Dioon planifolium and Dioon purpusii (Gutiérrez-Ortega and co-authors, 2021). When it was described, the abstract counted 17 species in the genus; The World List of Cycads now accepts 19, the most recent being Dioon nuusaviorum, described in 2026.

Etymology and history

The epithet honours Silvia Hortensia Salas-Morales, co-founder of the Sociedad para el Estudio de los Recursos Bióticos de Oaxaca (SERBO), for her contributions to the knowledge of the flora and forests of Oaxaca, and in particular for the discovery of numerous cycad populations (The World List of Cycads, after Haynes, 2022). She is a co-author of several other names in the genus, including Dioon argenteum (2003), Dioon planifolium (2016) and Dioon oaxacensis (2020), and of the raising of Dioon sonorense to species rank (published in 1998). The name of the genus comes from the Greek dis, “two”, and ôon, “egg”, for the two seeds on each scale of the female cone.

The Montgomery Botanical Center catalogue lists three accessions under this name, all from 2004, well before the description, which suggests that material from these populations was grown there long before the species was named. Nothing else is documented about its introduction into cultivation.

Common names

No common name is attested for Dioon salas-moralesiae, in English or any other language. The names espadaña and nimalari, given to Dioon merolae by the 2010 list of the Mexican standard NOM-059-SEMARNAT-2010, are attached to Chiapas and cannot be transferred to this species.

In the wild

Dioon salas-moralesiae is endemic to south-eastern Oaxaca, west of the Isthmus of Tehuantepec, the narrowest part of Mexico between the Pacific and the Gulf of Mexico. The two localities named in the article are San Miguel Tenango, the type locality, and Santiago Lachiguiri; the coordinates of the populations are not published.

The altitude, vegetation and climate of its localities are not given in the abstract, key and figure captions. The 2020 study shows only that the three lineages of the former Dioon merolae are isolated by habitats unsuitable for cycads, and that they have kept the same ecological niche despite different local conditions, which the authors call niche conservatism.

Conservation status and regulation

Dioon salas-moralesiae has not yet been assessed by the IUCN (Not Evaluated, NE, according to The World List of Cycads and GBIF). Before 2021 its populations were part of Dioon merolae, listed as Vulnerable (VU) in 2022; the split mechanically reduces the range of each species, but no new assessment has been published.

The species has no record of its own in Species+, but it is covered by the listing of all cycads (Cycadales spp.), which includes the whole family Zamiaceae, in CITES Appendix II since 1977. Annotation #4, in its version of 5 March 2026, exempts seeds, pollen, in vitro cultures in sterile containers and cut flowers. In the European Union these plants are in Annex B (Regulation (EU) 2026/1383, in force since 29 June 2026). In Mexico, neither the 2010 list of the NOM-059-SEMARNAT-2010 standard nor its 2019 update names the species; both class Dioon merolae, to which these populations then belonged, as “in danger of extinction” (P). Databases checked on 26 October 2026: check the regulations in force before any purchase or import.

Growing Dioon salas-moralesiae

No cultivation data have been published for Dioon salas-moralesiae. The species, described recently, does not appear in any growers’ forum report or in the catalogues of specialist nurseries under its own name, and the two American gardens that hold it have published nothing on its behaviour. The habitat data needed to deduce its needs are not available either. For the general principles of growing Dioon, see the genus page.

Outdoor and in-ground cultivation

No outdoor planting is documented anywhere, and no observation of the species has been published for the Jardin zoologique tropical at La Londe-les-Maures, in the Var.

Container cultivation

In climates with frost, a pot with a free-draining mineral mix, kept frost-free and dry in winter, is the prudent option until anything is known about its tolerance.

In cultivation in the UK, US and Australia

  • United Kingdom: no British garden declares the species to BGCI PlantSearch.
  • United States: the Montgomery Botanical Center (Coral Gables, Florida) lists three accessions in its online catalogue, all from 2004; Naples Botanical Garden (Florida) also declares the species to BGCI PlantSearch. A BGCI listing is a declaration by the garden, not proof that the plant is alive today.
  • Australia: no Australian garden declares the species to BGCI.

Propagation

No propagation data specific to Dioon salas-moralesiae have been published. As with other cycads, sowing fresh seed is the normal route; seeds are exempt from CITES permits.

Pests and diseases

No disease or pest is documented for Dioon salas-moralesiae.

Cold hardiness

The cold tolerance of Dioon salas-moralesiae is not known: no measurement, no cultivation report and no nursery estimate has been published.

Mediterranean and European experience

No cultivation report is documented in France or Italy, or elsewhere in Mediterranean Europe.

United Kingdom, United States and Australia

No report from a British, American or Australian grower has been found. The hardiness values shown by some websites for this species rest on no published observation, and the figures known for Dioon merolae cannot be transferred to it.

Toxicity and precautions

No toxicity analysis has been published for Dioon salas-moralesiae, but it should be treated as toxic. Cycads contain toxic glycosides (cycasin, macrozamin), from which methylazoxymethanol is derived, a toxin affecting the liver and the nervous system. The risk is documented mainly in other cycads, for dogs that chew the seeds and for livestock. Wear gloves to handle the seeds and keep them out of reach of children and animals. If any part has been eaten, contact a poison centre, a doctor or a vet without delay.

Traditional uses

No traditional use of Dioon salas-moralesiae is documented.

Frequently asked questions

Should it be spelt salas-moralesiae or salas-moralesae?

Both refer to the same species. The name was published in 2021 as salas-moralesae; IPNI and The World List of Cycads use the corrected form salas-moralesiae, which this page follows.

How does it differ from Dioon merolae?

Mainly in the leaflets and the provenance. Dioon salas-moralesiae has broad leaflets that overlap little and are only slightly curved at the tip; Dioon merolae has strongly overlapping leaflets, strongly curved downwards. The first grows west of the Isthmus of Tehuantepec, in Oaxaca, the second to the east, notably in Chiapas.

Can Dioon salas-moralesiae be bought?

Not as far as is known. No offer under this name is documented. A plant labelled Dioon merolae without provenance might belong to either species, with no way of checking.

Is it hardy?

Not known. No cold trial has been published, and no reliable value can be given.

Is it protected?

Yes. It is covered by CITES Appendix II and by Annex B in the European Union, like all cycads not listed in Appendix I. It has no IUCN category of its own yet.

Is it toxic?

Yes, as a precaution. There is no analysis for the species, but the cycads studied contain dangerous toxins, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Gutiérrez-Ortega, J.S., Pérez-Farrera, M.A., Chemnick, J. & Gregory, T.J. (2021). A reassessment of Dioon merolae (Zamiaceae) leads to the description of Dioon salas-moralesae, a new cycad species from Southeastern Oaxaca, Mexico. Phytotaxa 528(2): 93–110. doi:10.11646/phytotaxa.528.2.3 [Protologue; abstract, key and figure captions.]
  • Gutiérrez-Ortega, J.S., Salinas-Rodríguez, M.M., Ito, T. et al. (2020a). Niche conservatism promotes speciation in cycads: the case of Dioon merolae (Zamiaceae) in Mexico. New Phytologist 227(6): 1872–1884. doi:10.1111/nph.16647 [Three lineages within the former Dioon merolae, niche conservatism; abstract.]
  • Gutiérrez-Ortega, J.S., Pérez-Farrera, M.A., Vovides, A.P., Salas-Morales, S.H. & Chemnick, J. (2020b). Dioon oaxacensis (Zamiaceae): a new cycad species from the arid central valleys of Oaxaca (Mexico). Phytotaxa 474(1): 51–61. doi:10.11646/phytotaxa.474.1.5 [Characters of the neighbouring species; abstract.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Etymology, as 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. doi:10.5281/zenodo.21958524 [Reference checklist.]