genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
epiphytic
An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...
Hylocereeae
The Hylocereeae are a tribe of cacti. Most are found in the tropical forests of Central and northern South America, and are climbers or epiphytes, unlike most cacti. The tribe includes between six and eight genera in different circumscriptions ...
Central America
Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...
. It should not be confused with '' Discocactus'', which is a different genus.
Species of ''Disocactus'' grow in
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
regions either on trees as epiphytes or on rocks as
lithophyte
Lithophytes are plants that grow in or on rocks. They can be classified as either epilithic (or epipetric) or endolithic; epilithic lithophytes grow on the surfaces of rocks, while endolithic lithophytes grow in the crevices of rocks (and are als ...
s. 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 hybrid
Epiphyllum hybrids, epiphyllums, epicacti, or just epis, also known as orchid cacti, which are widely grown for their flowers, are artificial hybrids of species within the group of cacti placed in the tribe Hylocereeae. In spite of the common nam ...
s or just epiphyllums are derived from crosses between species of ''Disocactus'' (rather than ''
Epiphyllum
''Epiphyllum'' (; "upon the leaf" in Greek) is a genus of epiphytic plants in the cactus family (Cactaceae), native to Central America and South America. Common names for these species include climbing cacti, orchid cacti and leaf cacti, though ...
'') and other genera in the Hylocereeae., p. 286
Description
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.
The large flowers open during the day, appearing singly or rarely in groups from an areole. They are of different shapes and sizes, 10–15 cm 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 3–5 mm 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 10–30 mm long and 3–7 mm wide, yellow-green; the petaloid parts are 6–8 cm long and 1.5–2 cm wide, orange, reddish at base. The stamens are asymmetrically grouped along the lower side of the throat of the perianth; the style is exserted, 9–13 cm long with 8–9 stigma lobes.
Berry-like ellipsoid fruits are formed that are 7 cm long and 3 cm in diameter, almost bare or covered with a few small scales. They contain broad ovate seeds 1.5 to 2.4 millimeters long and 1 to 1.7 millimeters 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.
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'':
*''Bonifazia'' Standl. & Steyerm.
*''Chiapasia'' Britton &
Rose
A rose is either a woody perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be ...
*''Heliocereus'' (A.Berger) Britton & Rose
*''Lobeira''
Alexander
Alexander is a male given name. The most prominent bearer of the name is Alexander the Great, the king of the Ancient Greek kingdom of Macedonia who created one of the largest empires in ancient history.
Variants listed here are Aleksandar, Al ...
Rose
A rose is either a woody perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be ...