Name and origin
Turbinicarpus valdezianus occurs naturally in northeastern Mexico. The species was initially described as Pelecyphora valdeziana. It also appeared in the literature as Normanbokea valdeziana and Gymnocactus valdezianus. POWO treats T. valdezianus var. albiflorus as a synonym of the species, so publications under that name refer to the white-flowered material distinguished by their authors within the currently accepted species. [2-WWW]
Material for the spine-microstructure study came from seeds labelled TCG 2001, with Saltillo in Coahuila as the locality. Plants grew in the author's collection. This information links the microscopic description to documented provenance, rather than treating a single sample as a measurement of all species populations. [Mosco 2009, p. 120–122, tab. 1]
Pierzaste ciernie
Long projections of epidermal cells extend away from the spine axis and form a feathery surface. The epidermis was continuous, and fibre walls inside radial spines were thick. In the study table, their mean thickness was 4.1 ± 0.9 µm. The value is a mean with variability of cell measurements in preparations of the studied material. For this species, technical difficulties meant the author made ten to twenty measurements of a given trait. [Mosco 2009, p. 120, 122, tab. 2]
The feathery appearance persists in adult plants. Mosco interprets it as retention of a feature found in juvenile cacti, or neoteny. Shielding the stem surface with a dense spine layer is a proposed explanation of its significance. The study contains no measurements of light reaching the stem or photosynthesis under this covering, so the function remains a hypothesis relating to the observed structure. [Mosco 2009, p. 126–127]
Stem tissues
In the anatomical study, epidermal cells viewed from above had an elongated polygonal outline and wavy side walls. Prismatic crystals occurred beneath the epidermis. Druses, crystal clusters of a different geometry, were found in the pith. The two types therefore occurred in different parts of the same stem. [De la Rosa-Tilapa et al. 2019, wersja online, p. 2–3, ryc. 1C]
Deeper tissues included photosynthetic and storage parenchyma, while xylem contained vessels and wide-band tracheids. This structure combines conduction with a high proportion of parenchyma. Observing preparations describes the tissue condition of specific material, while the amount of water stored and drought responses are established through physiological experiments. [De la Rosa-Tilapa et al. 2019, online version, pp. 2–4]
In vitro propagation and hyperhydricity
In vitro shoots can develop excessive hydration, becoming glassy and brittle. García Osuna and colleagues compared several medium additives in T. valdezianus. All treatments contained kinetin. In the system studied, paclobutrazol increased new-shoot number, and no hyperhydricity symptoms occurred in this treatment. Prohexadione-calcium, salicylic acid and benzoic acid increased the proportion of explants with symptoms relative to the control. [García Osuna et al. 2011, p. 176–178, tab. 1]
Explants were grown on agar-solidified MS medium under controlled light and temperature conditions. The result concerns shoot culture and the growth-regulator concentration used. A separate article on hyperhydricity presents the experimental conditions, percentages of explants with symptoms and differences between multiplication and rooting. These stages require separate assessments of plant quality. [García Osuna et al. 2011, p. 176–179]
Related articles
Materials from the author's archive
The species also appears in Konrad Szychowski's private material archive. [Kaktusy i Inne 2005c, file p. 24] [Kaktologia 2009a, file p. 7] [Kaktologia 2009b, file p. 17] [Neciu b.d., file p. 1] [Kaktusy i Inne 2006b, file p. 6]
Synonyms and names in the literature
Pelecyphora valdeziana · Normanbokea valdeziana · Neolloydia valdeziana · Thelocactus valdezianus · Gymnocactus valdezianus · Mammillaria valdeziana · Echinocactus valdezianus · Pelecyphora plumosa · Turbinicarpus valdezianus var. albiflorus · Turbinicarpus valdezianus var. pazoutii [2-WWW]