Pediocactus paradinei

A species of the Kaibab Plateau

POWO accepts Pediocactus paradinei as native to northern Arizona. The names P. simpsonii var. paradinei and Pilocanthus paradinei are its synonyms. The floristic description places sites on the Kaibab Plateau, in gravelly limestone soils at elevations of 1500–2100 m above sea level. The species grows among junipers and pines, and also in grassy areas. [2-WWW] [Heil and Porter 2003a, POWO. Flora of North America, P. paradinei]

Flexible spines and spring flowers

The stem is usually solitary and spherical, 3–7.5 cm high and 2.5–5.5 cm wide, exceptionally up to 8 cm. In adult plants, numerous hair-like white or grey spines shelter it. There are 13–22 radial spines, 20–25 mm long, and 3–6 central spines, 8–35 mm long. Spring flowers are light yellow or pink, 1.9–2.5 cm in diameter. Black seeds have a papillose surface without pronounced wrinkling. [Heil and Porter 2003a, Flora of North America, P. paradinei]

Neighbouring vegetation and future habitats

In 2022, Colombo and her co-authors compared sites previously studied in 2005. Over seventeen years, plant richness declined, particularly herbs flowering around the same time as the cactus. Ground-surface cover also changed. The authors consider these changes as possible influences on native bee habitats. In distribution models, precipitation seasonality, temperature evenness and mean temperature of the coldest quarter were important. Projections indicated contraction and shifts in climatically suitable areas by mid-century. [Colombo et al. 2026, article abstract, 2005–2022 comparison and distribution models]

The available abstract describes habitat changes and model results. It gives no measurements of pollination effectiveness or demonstrated decline in bee abundance. The relationship between changes in surrounding vegetation and cactus reproduction remains an ecological hypothesis within this scope. [Colombo et al. 2026, scope of information in the abstract]

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