Ariocarpus retusus subsp. trigonus

Body to over 20 cm wide. Tubercles smooth. Flowers yellow.

NE Mexico

 

Other species without tubercular grooves but with white or pink to magenta flowers include: A. retusus Scheidw. from NE Mexico with tubercles hardly longer than broad; A. agavoides (Castañeda) E.F. Anderson from NE Mexico (Tamaulipas) with a woolly areole above; and A. scaphorostrus Boed. from NE Mexico (Nuevo Leon) which is woolly at the base of the tubercles but without a groove or areole.

Source: Thompson, A, ; Forbes, S.; Spencer, R. (1997). Cactaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press. (as Ariocarpus trigonus)

kingdom Plantae
phylum   Tracheophyta
class    Magnoliopsida
superorder     Caryophyllanae
order      Caryophyllales
family       Cactaceae
species        Ariocarpus retusus