Cycas hainanensis C.J.Chen is not an accepted species. It is a taxonomic synonym of Cycas taiwaniana Carruth., a tropical cycad of the genus Cycas endemic to Hainan Island and the far southern fringe of mainland China. The full species profile — taxonomy, ecology, morphology, conservation, and cultivation — is available on our Cycas taiwaniana page.
Why two names for the same plant?
Cycas taiwaniana was described first, by William Carruthers in 1893, from a cultivated specimen at Kew that he incorrectly believed came from Taiwan. The name stuck — but the real origin of the species remained unclear for over a century. Meanwhile, C.J. Chen described Cycas hainanensis in 1975 from wild material collected on Hainan Island, believing it to be a new, distinct species.
For decades, both names coexisted in the literature. Cycas hainanensis was widely used in Chinese conservation documents, botanical garden records, and the domestic nursery trade, while Cycas taiwaniana circulated internationally — often misapplied to the Taiwanese species that is now correctly called Cycas taitungensis.
The molecular species delimitation study by Feng et al. (2021, Taxon) resolved the situation definitively. Using both chloroplast and nuclear DNA markers across comprehensive sampling, the study demonstrated that Cycas hainanensis and several other named taxa from Hainan — Cycas changjiangensis N.Liu, Cycas lingshuigensis G.A.Fu, and Cycas shanyaensis G.A.Fu — are genetically indistinguishable from Cycas taiwaniana. All represent the same species on Hainan Island, described multiple times from different localities. Under the principle of nomenclatural priority, Cycas taiwaniana (1893) takes precedence over Cycas hainanensis (1975).
This treatment is accepted by POWO (Plants of the World Online, Royal Botanic Gardens Kew), the nomenclatural authority followed by succulentes.net.
Where you may still encounter the name Cycas hainanensis
Despite its synonym status, the name Cycas hainanensis remains in active circulation in several contexts. Chinese conservation literature and government protection lists frequently use hainanensis rather than taiwaniana, partly because the name more accurately reflects the species’ geographic reality (it is from Hainan; it is not from Taiwan), and partly because bureaucratic nomenclature changes lag behind taxonomic revisions. The IUCN Red List maintained a separate assessment for Cycas hainanensis (Endangered) that predates the synonymy. Specialist nurseries, particularly in Asia, may label plants as Cycas hainanensis rather than Cycas taiwaniana. Botanical garden accession records and herbarium labels created before 2021 use the older name.
If you encounter a plant labeled Cycas hainanensis in a nursery, a botanical garden, or a publication, it is the same species as Cycas taiwaniana. The cultivation requirements, conservation status, and biological characteristics are identical.
Summary of synonymy
| Name | Author | Year | Status |
|---|---|---|---|
| Cycas taiwaniana | Carruth. | 1893 | Accepted name (POWO) |
| Cycas hainanensis | C.J.Chen | 1975 | Synonym |
| Cycas changjiangensis | N.Liu | 1998 | Synonym |
| Cycas lingshuigensis | G.A.Fu | 2004 | Synonym |
| Cycas shanyaensis | G.A.Fu | 2006 | Synonym |
References
- Carruthers, W. (1893). Cycas taiwaniana, sp. nov. Journal of Botany, 31, 1–3, pl. 331.
- Cheng, C.Y., Cheng, W.C. & Fu, L.K. (1975). Cycas hainanensis, a new species. Acta Phytotaxonomica Sinica, 13(4), 82.
- Feng, X.Y. et al. (2021). Species delimitation with distinct methods based on molecular data to elucidate species boundaries in the Cycas taiwaniana complex (Cycadaceae). Taxon, 70(3), 477–491.