Description: Ariocarpus retusus is the
largest species of the genus characterised by long tubercles slightly
projecting above ground level. The crested form is
rarer than the normal plant, and it is particularly sought after by
can get quite large making a spectacular specimen.
Stem: Grey, or blue-green, flattened 10-25cm thick.
Tubercles: Leaf-like, divergent, erect,
basally compressed, usually becoming attenuate at the apices, convex or
adaxially and often with shallow adaxial undulations or wrinkling,
not fissured, 1.5-4cm long, 1-3.5cm wide, nearly as wide as long;
Areoles: at the tips of the tubercles, rounded, 1-5mm in diameter.
Flowers: Diurnal 4-5cm in diameter., 2-4 2cm long; white to pink
(or magenta), occasionally with reddish midribs,
Root: Swollen and very large tap root
Flowering time: October
Fruit: white, green, or rarely pinkish, 10-25mm long, 3-10mm in
Ariocarpus retusus is an extremely variable species. Also crested
plants may be quite different one to each other.