Structure and identification
The monograph describes broad clusters of flattened, dark green stems. Much of the body lies below ground and continues into a long taproot. Tubercles are rounded, slightly flattened above. The few lateral spines spread almost horizontally, and central spines are absent. Flowers are creamy white. The authors also recorded a population group producing underground stolons. [Dicht and Lüthy 2005, p. 153]
Habitat and variation
The sites described lie in San Luis Potosí, primarily in the Las Tablas area. The monograph associates the species with grassy plains of a former lake on gypsum substrate. The underground position of part of the stem and the well-developed root are morphological traits of adult plants. The results of the 2025 experiment concern young plants grown for five years in a greenhouse. [Dicht and Lüthy 2005, p. 153; art. 105461, sekcja 2.2] [Guerra-Coss et al. 2025, p. 153; art. 105461, sekcja 2.2]
Mesquite shelter during experimental warming
The 2025 field experiment used 80 plants grown from seed and kept in a greenhouse for five years. They were planted in San Luis Potosí, beneath canopies of the mesquite Neltuma laevigata and in adjacent open habitat. In each habitat, 20 plants were warmed in open-top chambers and 20 were left as controls. After planting, each received a single 20 ml dose of water. Plants were then left unwatered for 266 days, from 26 April 2024 to 17 January 2025. Control plots were surrounded by mesh limiting herbivore access. [Guerra-Coss et al. 2025, art. 105461, sekcje 2.1–2.3]
Warming increased mean air temperature in the open habitat by 1.4°C and the maximum by 4.1°C. Beneath mesquite, the increases were 1.0°C and 2.8°C, respectively. Under the canopies, 100% of control plants and 95% of warmed plants survived. In the open area, 90% of controls and none of the warmed plants survived. Each group contained 20 plants. Measurements showed less water in the soil beneath trees than in the open habitat. The canopies reduced radiation exposure and limited air heating. The results indicate protection of young plants from heat and light stress in this experiment. Stem temperatures and photochemical processes were not measured. [Guerra-Coss et al. 2025, art. 105461, p. 4–6 PDF, tab. 2, ryc. 3–4]
Related articles
Materials from the author's archive
The species also appears in Konrad Szychowski's private material archive. [Neciu b.d., file p. 1]