Family Cactaceae > Subfamily Cactoideae > Tribe Hylocereeae.
There are around 19 (10) species from Central America.
Common names such as Orchid Cactus, Night-blooming cactus, Queen or Princess of the
    Night and Jungle Cactus are used for a number of species in this and other genera.
Most plants seen in cultivation are hybrids of species in other similar genera.

Most are sprawling epiphytes with long, leafless stems that are flattened or sometimes angled.
The stems, usually with scalloped or lobed edges, are sometimes segmented.
Juvenile stems have more rounded bases.
Stems are up to 5 cm wide and aerial roots are common.
Some produce runners or stolons up to 3 m long that root when they touch a suitable site.

The areoles have hairs, scales or bristles formed from modified leaves.
Adult stems have no spines but there may be some in areoles on juvenile stems.
Areoles may also contain extrafloral nectaries.

Flowers, from areoles on the sides of the stems, are nocturnal and die the following day.
They are large and white, sometimes with yellow or pink tinges.
The perianth consists of undifferentiated tepals.
The bases of the tepals are fused to form a long tubular hypanthium.
This can be smooth or have bracts or scales. There are no spines.
The numerous stamens insert into the upper part of the hypanthium.

The hypanthium inserts onto the pericarpel which is tissue from the top of the stem.
The pericarpel surrounds the inferior ovary which contains numerous ovules.
The single style divides into up to 10 stigmas.
The fruit are berries up to 4 cm long.

Epiphyllum hybrids (Epis).
A few species such as Epiphyllum hookeri and E. oxypetalum are cultivated but the vast
    majority of plants called ‘Epiphyllums’ are hybrid cultivars.
A few of these have a true Epiphyllum as a parent but many involve species from related
    genera such as Disocactus, Pseudorhipsalis and Selenicereus.

The over 13,000 registered hybrids mainly differ in the flower colour and size.
Flowers can be a few cms across up to 25 cm with the majority being shades of red with some white to cream.