Scientific taxonomy article
Accepted name and publication history
The current Kew backbone accepts Mammillaria hahniana; the standardized author citation is Werderm. Erich Werdermann published the name in 1929 in Monatsschrift der Deutschen Kakteen-Gesellschaft 1: 77. IPNI supplies nomenclatural authorship and place of publication, while current acceptance, synonymy, and native distribution follow POWO.12
The name was published directly in Mammillaria. The species node has only the homotypic synonym Neomammillaria hahniana, while Kew preserves four accepted subspecies as separate child boundaries.
Taxon boundary and infraspecific treatment
In the Kaktüs Doktoru backbone, the species is a child of Mammillaria. Kew accepts subsp. bravoae, the nominal subsp. hahniana, subsp. mendeliana, and subsp. woodsii. These four records are not converted into species synonyms, and the batch updates only the parent species node. This package updates only the canonical species node and its linked botanical-dictionary record; it does not rewrite the genus, flatten accepted subordinate ranks into species synonymy, or alter the product.
Diagnostic characters
The species may have a globose to short-cylindrical stem, dense white wool and hair-like radial spines, stronger central spines, and usually pink-to-magenta flowers. Wool density varies in cultivation and is not a complete diagnosis on its own. Members of Mammillaria have distinct tubercles rather than continuous ribs, and flowers generally arise from reproductive areoles in the tubercle axils. Identification should not be reduced to one spine colour or a commercial photograph; tubercles, areoles, spines, flowers, fruits, and provenance should be assessed together.3
Phylogenetic context
A 2021 molecular study showed that the traditional broad concept of Mammillaria was not a single natural lineage and that generic limits within the mammilloid clade required reassessment.4 The current Kew backbone nevertheless accepts this species in Mammillaria. Phylogenetic context does not automatically rename the accepted species; it explains why historical generic combinations and appearance-based groupings must be checked against a maintained backbone.
Native distribution and conservation
Kew records the native range as north-eastern Mexico to Jalisco.1 POWO records the species as a succulent subshrub of desert and dry-shrubland biomes. The four accepted subspecies show why one densely woolly commercial specimen cannot represent all variation within the species. The stored conservation category is NT.5 The IUCN assessment assigns Near Threatened, so the previous live LC field should be corrected to NT. Nursery availability does not cancel pressure on wild populations.
Synonymy and retrieval
Kew accepts 1 synonym at the species node: Neomammillaria hahniana is the single homotypic combination based on the same nomenclatural type. These are not canonical routes; they document nomenclatural history and support retrieval of older literature. The four accepted subspecies and common names such as “Old Lady Cactus” are not species synonyms.1
References
- Plants of the World Online. “Mammillaria hahniana Werderm.” Royal Botanic Gardens, Kew. Accessed: 2026-08-04. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:151068-2 ↩
- International Plant Names Index. “Mammillaria hahniana Werderm.” Accessed: 2026-08-04. https://www.ipni.org/n/134657-1 ↩
- World Flora Online. “Mammillaria hahniana Werderm.” Accessed: 2026-08-04. https://www.worldfloraonline.org/taxon/wfo-0001248755 ↩
- Breslin, P. B., Wojciechowski, M. F. & Majure, L. C. “Phylogenetic relationships within Mammillaria (Cactaceae) and implications for the circumscription of the genus.” Taxon 70(2): 308–323. https://doi.org/10.1002/tax.12451 ↩
- IUCN Red List of Threatened Species. “Mammillaria hahniana.” https://www.iucnredlist.org/species/151925/121513859 ↩
