Disocactus is a genus of epiphytic cacti in the tribe Hylocereeae found in Central America, the Caribbean and northern South America. It should not be confused with Discocactus, which is a different genus.
Species of Disocactus grow in tropical regions either on trees as epiphytes or on rocks as lithophytes. They have two distinct growth habits. Species such as D. phyllanthoides have stems which are round at the base but then become flattened and leaflike.
Many of the cultivated plants known as epiphyllum hybrids or just epiphyllums are derived from crosses between species of Disocactus (rather than Epiphyllum) and other genera in the Hylocereeae.
The flattened stems, which evolved this way because there is no need for the plant to store that much water in tropical conditions, make it possible for the cacti to capture the sun more efficiently.
The species of the genus Disocactus grow as epiphytes or lithophytes and are shrubby, profusely branched, hanging, up to 3 m long. The shoots are ribbed or flattened, 3-angled or flattened, ribbon-like, 3–10 mm wide, remotely crenate and leaf-like. The main shoot, which rotates near the base, is only flattened at the top, while the side shoots are completely flattened. The thorns on the areoles are bare or with white wool and bristles 4–9 mm long.
Genus name: Greek dis- 'twice' + Greek isos 'equal' + Cactus. Named “in allusion to the distinctive character of the genus”, i.e. the tepals and sepals being equal in number and “similar in form and colour” (Lindley).
