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Wikipedia / Disocactus

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.

Description

The species of the genus Disocactus grow as epiphytes or lithophytes and are shrubby, profusely branched, hanging, up to 3m long. The shoots are ribbed or flattened, 3-angled or flattened, ribbon-like, 3–10mm 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 4–9mm long.

The large flowers open during the day, appearing singly or rarely in groups from an areole. They are of different shapes and sizes, 10–15cm long. The flowers are funnel-shaped or tubular, sometimes zygomorphic and rarely wheel-shaped, receptacular tube curved, embraced by foliaceous scales or 1–few bristles 3–5mm long. They are bright red, orange, slightly reddish pinkish-orange, light yellow in color, or white. The stamens are often in two rows, with the upper ones sometimes forming a clear throat circle. The sepaloid parts of perianth are 10–30mm long and 3–7mm wide, yellow-green; the petaloid parts are 6–8cm long and 1.5–2cm wide, orange, reddish at base. The stamens are asymmetrically grouped along the lower side of the throat of the perianth; the style is exserted, 9–13cm long with 8–9 stigma lobes.

Berry-like ellipsoid fruits are formed that are 7cm long and 3cm in diameter, almost bare or covered with a few small scales. They contain broad ovate seeds 1.5 to 2.4millimeters long and 1 to 1.7millimeters wide. The seeds are brown-black to almost black and are shiny or, more rarely, somewhat dull.

Taxonomy

Pseudorhipsalis is sometimes included in Disocactus, but it is kept separate by the International Cactaceae Systematics Group. Aporocactus is formerly included in Disocactus, but it should be a genus on its own according to molecular evidence.

Species

, Plants of the World Online accepted the following species:

Synonymy

The boundaries of the genera in the tribe Hylocereeae have been subject to considerable change and uncertainty, which is reflected in the number of names which have been used for Disocactus:

Cultivation

References