Turbinicarpus alonsoi

Name, range and origin of the material studied

Turbinicarpus alonsoi is an accepted species, described under this name in 1996. POWO gives its natural range as Guanajuato and San Luis Potosí in Mexico and dry scrub environments. Pediocactus alonsoi is a synonym. [2-WWW]

In the spine study, Mosco used plants raised from documented seeds labelled TCG 21001, originating from Xichú in Guanajuato. The collection was maintained under dry conditions. Spine surfaces were examined by electron microscopy, and sections and individual fibres by light microscopy. [Mosco 2009, p. 120–123, tab. 1–2]

Stem, flowers and seeds

The regional Bajío flora describes a solitary, spherical and flattened stem up to 3 cm high and around 7 cm wide, with specimens reaching 9 cm. The green surface has a bluish tint. Triangular tubercles, 3–4 mm long, are arranged in rows forming up to 13 ribs. Round areoles bear 3–5 flexible, awl-shaped spines up to 2 cm long. Spines are grey with darker tips. [Arias and Aquino 2019, p. 273]

Flowers are usually 2–3.5 cm long and 2–2.8 cm wide, with described extremes of 3.8 and 3 cm, respectively. The tepals are magenta, with a paler margin on some outer tepals. Stamen filaments and style are pink. The yellow stigma divides into 4–5 lobes. The spherical, brown fruit, 9–10 mm long, has a bare surface. Black seeds measure around 1 mm. [Arias and Aquino 2019, p. 273]

Habitat and flowering in Guanajuato

The 2019 account documents the species in northeastern Guanajuato, in tropical forest whose trees shed their leaves in the dry season, at around 1000 m elevation. It gives flowering from November to February. The data refer to regional Mexican material. The authors identify habitat transformation and direct plant collecting as threats within the small area of occurrence. [Arias and Aquino 2019, p. 273–274]

Ciernie o korkowej fakturze

Mature spines of the material studied had a corky texture, blunt tips and a cracked surface. Transverse fissures extended through the epidermis and deeper strengthening tissue. The term corky describes spine appearance and properties. Its interior consists of sclerenchyma fibres, cells of strengthening tissue, surrounded by a sclerified epidermis. [Mosco 2009, p. 123–126, tab. 2]

Thin-walled fibres had broad cell lumens and left spaces between cells. The author linked tissue delicacy to susceptibility to fissure formation during growth. Spine architecture helps explain its texture. The study involved microscopic observation and stiffness assessment, without measuring the force needed to break a spine. [Mosco 2009, pp. 123–127]

Epidermis and gas exchange

In the comparison of stem anatomy, T. alonsoi was the only taxon studied with a distinctly convex outer wall of epidermal cells. A fine relief is therefore visible on the surface, arising from individual cell shapes. Stomata were sunken relative to neighbouring cell surfaces. [De la Rosa-Tilapa et al. 2019, wersja online, p. 2, ryc. 2D–E]

The depression creates a space between the stomatal apparatus and stem surface. Its role in water balance also depends on stomatal opening and surrounding conditions. The study assessed anatomical preparations, so this feature description remains separate from measuring transpiration or determining the plant's dehydration limit. [De la Rosa-Tilapa et al. 2019, wersja online, p. 1–2, 7–9]

Bundles in storage parenchyma

The stem cortex contains photosynthetic and storage parenchyma. Amphicribral bundles were found there in T. alonsoi. Xylem lies at the centre of such a bundle, surrounded by phloem. Most other turbinicarpi studied had collateral bundles, with xylem and phloem beside one another. The amphicribral arrangement also occurred in T. lophophoroides and Rapicactus subterraneus (called Turbinicarpus subterraneus in the study). [De la Rosa-Tilapa et al. 2019, online version, p. 2, Fig. 3B]

The hypodermis contained prismatic crystals, and druses were observed in the pith. Xylem of the main cylinder had vessels among wide-band tracheids and lacked fibres. The structure of a small cortical bundle and that of the whole vascular cylinder describe different levels of stem organisation. [De la Rosa-Tilapa et al. 2019, online version, pp. 2–4]

Cultivation and grafting in archival material

An account preserved in Konrad Szychowski's private archive, in “Kaktologia” from 2009, describes a gravel substrate with added limestone and good seed germination. It reports flowering after around two years for plants grafted onto Pereskiopsis, and after around three to five years on their own roots. These are cultivation observations cited in that article. The available archival record lacks the sizes of the compared groups and their full growing conditions. [Kaktologia 2009a, pp. 7]

The same material indicates that grafting can change tubercle form. Growth and flowering-age information can therefore be read alongside rootstock type and specimen management. The older account remains available at the archival account address. [Kaktologia 2009a, pp. 7]

Related articles

Materials from the author's archive

The species also appears in Konrad Szychowski's private material archive. [Kaktologia 2009a, file p. 7] [Kaktologia 2009b, file p. 17] [Neciu b.d., file p. 1]