Coryphantha ottonis

Structure and identification

The monograph describes solitary spherical or short-cylindrical stems with broad, rounded tubercles. Whitish yellow lateral spines are complemented by several stronger central spines. The main spine projects forwards and sometimes curves distinctly downwards. Red glands occur in the axils. Flowers have white inner tepals and a darker stripe on the outer side. Not all tubercles of flowering plants have a complete groove. [Dicht and Lüthy 2005, p. 62–63]

Habitat and variation

The authors document a range from Puebla and Tlaxcala to Zacatecas and Durango, primarily on flat lava substrates in pastures, sometimes beneath shrubs. They described sparser armature in the southeastern part of the range and stronger armature in the northwest. Variation passes gradually between these forms. [Dicht and Lüthy 2005, p. 62–63]

Water conduction in tubercles

The 2016 anatomical comparison covered 2 adult plants of this species, collected at natural sites during the rainy season. In the central vascular cylinder, vessels occurred in tissue rich in wide-band tracheids, whose walls have ring-like or spiral thickenings. Bundles reaching the tubercles contained vessel elements with smaller diameters than elements in the central cylinder. The authors proposed that this narrowing may restrict water flow to the tubercle. The assessment was based on preparations and cell dimensions, without direct flow measurements. [Terrazas et al. 2016, p. 2–8 PDF, tab. 1–2]

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