Coryphantha difficilis

Structure and identification

The stem is solitary, initially hemispherical, and may later elongate into a short cylinder. Tubercles are broad and flattened, and their obliquely truncated edges contribute to a tile-like arrangement. Lower lateral spines are shorter and stronger, while upper ones gather in a bundle. Several strong central spines point forwards and downwards. White wool covers the apex and young axils. Yellow flowers develop into rounded green fruits. [Dicht and Lüthy 2005, p. 148]

Habitat and variation

The monograph documents sites within Sierra de la Paila and the surrounding parts of Coahuila. Plants occur on alluvial plains and slopes with limestone gravel. Spine density varies locally, and heavily spined forms were also formerly called C. densispina. [Dicht and Lüthy 2005, p. 148]

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