Biology and generic limits
Comparison of six chloroplast markers showed that the historical broad treatment of Disocactus included separate lineages. Aporocactus species were placed in a different clade. Three species previously assigned to Epiphyllum were transferred to Disocactus. [Cruz et al. 2016, full source text, discussion of results]
The genus includes flattened, three-angled and multiribbed stems, bearing spines, bristles or neither. Floral architecture includes tubular, funnel-shaped and widely open forms. A species description combines these characters with the timing of flower opening and documented localities. [Cruz et al. 2016, full source text, discussion of results]