Habit and diagnostic traits
Plants in the original description reached 4 to 5 m in height, with stems 6 to 11 cm in diameter. They usually bore seven or eight ribs, occasionally nine. Areoles produced seven to nine radial spines and one to three central spines. The lower central spine was the longest, reaching up to 4.5 cm. Particularly useful diagnostic features are the tapering tips of mature branches and constrictions immediately above the areoles [Arreola-Nava and Terrazas 2004].
Flowers, fruits and phenology
Flowers develop near stem apices, open at night and reach 6.5 to 7 cm in length. Observations associated with the species description recorded flowering from June to August and mature fruit from August to September. Fruit are ovoid to globose, measure 5 to 6 cm in diameter and shed their bristly spines during maturation. Seeds are black and dull, with concave outer walls of the seed coat cells [Arreola-Nava and Terrazas 2004].
Distribution and habitat
The material documented by the authors came from Zopilote Canyon and the vicinity of San Francisco Ozomatlán in Guerrero. Sites were located in seasonally dry deciduous forest, together with other columnar cacti including S. beneckei and S. pruinosus. Herbarium specimens, field observations and morphological comparisons jointly support recognition of the species in this region [Arreola-Nava and Terrazas 2004].