Turbinicarpus schmiedickeanus

Species and subspecies

POWO accepts Turbinicarpus schmiedickeanus within a range in northeastern Mexico reaching Jalisco. The name was initially published as Echinocactus schmiedickeanus. The database lists 14 accepted lower-rank taxa, including the variety T. schmiedickeanus var. kupcakii. The number therefore includes subspecies and a variety together. [2-WWW]

The names Turbinicarpus flaviflorus, T. rioverdensis and T. klinkerianus found in older studies now correspond to the respective subspecies of T. schmiedickeanus. This rank is retained in the spine-study description because a result obtained for one subspecies describes its material. The thin-walled spine of subspecies flaviflorus has a different organisation from the spine of subspecies rioverdensis. [2-WWW] [Mosco 2009]

Papery and corky textures

In T. schmiedickeanus subsp. flaviflorus (called T. flaviflorus in the publication), the radial spines studied were papery, with a continuous epidermis and smooth surface. Thin-walled fibres with cell lumens were found inside. In subspecies rioverdensis (called T. rioverdensis in the publication), spines had a corky texture, cracked epidermis and more varied fibre structure. [Mosco 2009, p. 122–123, tab. 2]

Mosco described cracks extending from the surface into the thin-walled strengthening tissue. Under magnification, such a spine can have a loose structure with retained cell lumens and spaces between cells. The link to flexibility and delicacy follows from anatomical examination and qualitative spine assessment. Bending force and tensile strength values remain outside this study's scope. [Mosco 2009, pp. 123–127]

In subspecies klinkerianus, fissures extended through the epidermis and internal tissue. The author discusses an earlier experiment with a tracer, also detected near the areole after application to a spine. Mosco's own study concerned spine structure. The quantitative contribution of such transport to the whole plant's water supply remained unexplained. [Mosco 2009, p. 120, 123–127]

The stem surface and interior

In the comparison of stem anatomy, the hypodermis of T. schmiedickeanus had up to four cell layers. This is the number of layers in the material studied, rather than a fixed value at every age and section position. In subspecies andersonii and flaviflorus, the cuticle had a striate surface. Most other taxa compared had a smooth cuticle. [De la Rosa-Tilapa et al. 2019, wersja online, p. 2, ryc. 2A]

Prismatic crystals occurred in the hypodermis, and cortical parenchyma contained small vascular bundles. The main xylem of the lineage described was fibre-free, with wide-band tracheids and non-lignified rays. Differences in surface-layer thickness and cuticular relief supplement spine features when comparing material of individual subspecies. [De la Rosa-Tilapa et al. 2019, online version, pp. 2–4]

Complex boundaries in relationship analyses

In the 2019 analysis, T. schmiedickeanus in its then-current subspecies treatment did not form a group corresponding to all accepted complex boundaries. Some tree branches were poorly resolved. The authors indicated the need to increase the number of individuals studied from natural populations. The POWO treatment remains the basis for account names, while the publication describes unresolved biological relationships. [Vázquez-Sánchez et al. 2019, pp. 414–415] [2-WWW]

Subspecies identification and field number are valuable when comparing seedlings and adult plants. Collection material can retain specific provenance, as in the spine study. This allows observed appearance to be referred to the tested batch and avoids combining results from different populations under a single former species name. [Mosco 2009, Mosco, pp. 120–121. Vázquez-Sánchez et al., pp. 414–415] [Vázquez-Sánchez et al. 2019, Mosco, pp. 120–121. Vázquez-Sánchez et al., pp. 414–415]

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