Rebutia pseudodeminuta—Scarlet Crown Cactus. A cactus with many names; a situation, unfortunately, not uncommon for cactus. The genus Rebutia is considered polyphyletic, but wide differences exist among taxonomists who have studied the genus. A 2011 study trying to make sense of DNA analyses renamed the species Aylostera buiningiana but the name is not widely accepted. The authoritative Plant List maintained by Kew uses Rebutia pseudodeminuta. Literature from 1972 and later, including the label for this specimen, uses Rebutia buiningiana. Those interested in such matters should Google each of these three names plus the Botany 101-level Wikipedia article for the genus Rebutia. The species, widely available in the cactus trade, comes from Northern Argentina and adjoining Bolivia.

The flowers of this specimen measure 40 mm, the anthers & stamens together are 5 mm, and the spines are 5 mm (each pair of spines are thus 10 mm.)