EPIPHYLLUM HYBRID

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 one illustrated here is blooming in our garden at the moment and is probably a Disocactus × jenkinsonii is a hybrid between Disocactus phyllanthoides and Disocactus speciosus. It is perhaps the most commonly grown orchid cactus and seems to survive and flower under most conditions. It has a very complex taxonomic history and has been mistaken for Disocactus ackermannii for a long time.

And I thought my family history was complex!

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PRICKLY PEAR

Opuntia, commonly called prickly pear or pear cactus, is a genus of flowering plants in the cactus family Cactaceae. Prickly pears are also known as tuna (fruit), sabra, nopal ('paddle', plural nopales) from the Nahuatl word nōpalli for the pads, or nostle, from the Nahuatl word nōchtli for the fruit; or paddle cactus.

The genus is named for the Ancient Greek city of Opus, where, according to Theophrastus, an edible plant grew and could be propagated by rooting its leaves. The most common culinary species is the Indian fig opuntia (O. ficus-indica), which is seen here.

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PRICKLY PEARS

Opuntia, commonly called prickly pear, is a genus of flowering plants in the cactus family Cactaceae. Prickly pears are also known as tuna (fruit), sabra, nopal (paddle, plural nopales) from the Nahuatl word nōpalli for the pads, or nostle, from the Nahuatl word nōchtli for the fruit; or paddle cactus. The genus is named for the Ancient Greek city of Opus, where, according to Theophrastus, an edible plant grew and could be propagated by rooting its leaves. The most common culinary species is the Indian fig opuntia (O. ficus-indica).

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CACTUS FLOWER

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PRICKLY PEAR

Opuntia ficus-indica is a species of cactus that has long been a domesticated crop plant important in agricultural economies throughout arid and semiarid parts of the world. It is thought to possibly be native to Mexico. Some of the common English names for the plant and its fruit are: Indian fig, opuntia, barbary fig, cactus pear, spineless cactus, and prickly pear, although this last name has also been applied to other less common Opuntia species. In Mexican Spanish the plant is called nopal, while the fruit is called tuna, which are names also used in American English, especially as culinary terms.

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EPIPHYLLUM HYBRID

The plants known as epiphyllum hybrids, epiphyllums, epicacti or just epis, widely grown for their flowers, are artificial hybrids of species within the group of cacti placed in the tribe Hylocereeae, particularly species of Disocactus, Pseudorhipsalis and Selenicereus. In spite of the common name, species in the genus Epiphyllum are less often involved as parents of epiphyllum hybrids.

The parent species from which epiphyllum hybrids were bred are different in appearance and habit from most cacti. They are found in the tropical forests of Central America where they grow as climbers or on trees as epiphytes. They have leafless (or apparently leafless) flattened stems which act as the plant's photosynthetic organs. Relatively large flowers are borne on the sides of the stems; in many species they open at night.

Hybrids between Disocactus and Epiphyllum have been called ×Disophyllum or ×Aporophyllum. The Epiphyllum Society of America (the International Registration Authority for hybrids of the Tribe Hylocereeae) maintains a list of epiphyllum hybrids (and Hylocereeae species) which contained over 7,000 names in 1996.

Epiphyllum hybrids need different treatment from semi-desert cacti. They should be protected from direct sunlight, with preferably 75% shading at midday. They are not frost hardy, so need to be protected from freezing conditions. It is recommended that the growing medium allows rapid drainage of water and is open, with at least one third of coarse material to prevent compaction. Plants should be kept moist. High nitrogen fertilisers are not recommended; no fertiliser should be given during the winter rest period.

Propagating epiphyllum hybrids from cuttings is easy. Rooting hormone can be applied to the base of the cutting before it is allowed to dry for ten days or more so that the cut forms a callus. The cutting is then planted sufficiently deeply so that it can stand upright. Water is not given for two weeks, after which the growing medium is kept at least slightly moist. Plants can be misted. They are fast growing plants and should flower within two years. Epiphyllum hybrids should be re-potted every 2 to 3 years as they tend to deplete the nutrients in their growing medium.

We have about half dozen different Epiphyllum hybrids growing in pots and they do quite well outside in Melbourne's climate. All of them we have grown from cuttings, and I am not aware of their "official" name. This pink one is quite spectacular with blooms about 20 cm in diameter. They last a few days (up to seven) on the plant and they can even be cut at the base of the stem as a cut flower that lasts 4-5 days indoors.

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ECHINOPSIS

A photo of a lovely Echinopsis spp cactus flowering in the Royal Botanic Gardens in Melbourne. The only cactus genus that is more confusing than Echinopsis is that of Opuntia. In both cases, there is a great number of species (over 100) and a tremendous amount of variation. In Echinopsis plants range from very small, flattened-globose plants to quite large, treelike giants. As a result, there is a long list of synonymous names for many of the species. Some synonyms referring to other synonyms that refer to a subspecies of some seemingly distinct species. Sorting through these names often feels like a wild goose chase and is quite frustrating.

In more recent thinking, the previous two genera of Trichocereus and Lobivia are included with Echinopsis. However, it is not at all uncommon for enthusiasts to use all three names in discussion even if their labels read Echinopsis! This usage reflects the general (inexact) situation that the larger, columnar members are distinguished as Trichocereus while Lobivia includes a select group of smaller, not-as-spiny plants which typically flower from low on the plant similar to most Rebutia species. This leaves the bulk of plants referred to as Echinopsis to be mostly spiny, ribbed, globose plants.

The main factor that ties these plants together are their very large, showy flowers. These flowers are all very similar in structure – funnel shaped, with hairy/wooly scaled floral tubes which give rise to hairy, globular fruit filled with a soft, mushy pulp. The flowers seldom last more than a single day and may be diurnal or nocturnal depending on the species. These species hybridise easily and have resulted in a tremendous number of hybrids that some cactus growers specialise in or grow exclusively. There are certainly enough hybrids to keep even ardent hobbyists busy.

Because of their exceptional flowers, many Echinopsis species are found in garden centres and collections world-wide. The larger species (aka Trichocereus) are also popular landscape plants in warmer parts of the world. While there are a number of species common in cultivation, there are as many or more unknown hybrids in the trade. These hybrids are easy-to-grow and produce nice flowers, but buyer beware if exact names are desired. Plants of this genus are widespread throughout South America and inhabit a wide range of habitats and climates.

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EPIPHYLLUM

Epiphyllum crenatum is a species of cactus and one of the most important parents in creating the Epiphyllum-hybrids commonly cultivated throughout the world. It is cultivated for its beautiful diurnal flowers. It is found naturally from Mexico (Oaxaca & Chiapas) to Honduras. It is epiphytic (grows upon another plant) or lithophytic (grows on rocks) in moist or wet forests, sometimes in oak forests (1.750 m alt. or less).

It is an easily cultivated, fast growing epiphyte. Needs compost containing plenty of humus and sufficient moisture in summer. Should not be kept under 12°C in winter. Can be grown in semi-shade or full sun. Extra light in the early spring will stimulate budding. Flowers in late spring or early summer.

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MELBOURNE STREET TREES 101 - CEREUS

I am stretching the definition of "tree" by inlcuding this "succulent shrub" under its umbrella, but one cannot but be impressed by the sheer size and majestic presentation of this giant cactus. Cereus is a genus of cacti (family Cactaceae) including around 33 species of large columnar cacti from South America. The name is derived from Greek (κηρός) and Latin words meaning "wax" or "torch". The genus Cereus was one of the first cactus genera to be described; the circumscription varies depending on the authority. The term "cereus" is also sometimes used for a ceroid cactus, any cactus with a very elongated body, including columnar growth cacti and epiphytic cacti.

Cereus are shrubby or treelike, often attaining great heights (C. hexagonus, C. lamprospermus, C. trigonodendron up to 15 m). Most stems are angled or distinctly ribbed, ribs 3–14, usually well developed and have large areoles, usually bearing spines. Cephalium is not present, Cereus mortensenii develops pseudocephalium. Flowers are large, funnelform, 9–30 cm long, usually white, sometimes pink, purple, rarely cream, yellow, greenish, and open at night. Fruits are globose to ovoid to oblong, 3–13 cm long, fleshy, naked, usually red but sometimes yellow, pulp white, pink or red. Seeds large, curved ovoid, glossy black.

The specimen illustrated here is Cereus paraguyanus, and all but the last photo are from Melbourne's Botanic Garden. The last photo is from my neighbourhood in inner suburban Melbourne, just to prove how well suited our climate is to the growth of this cactus in Melbourne. In out back garden we have two of these cacti growing in large pots, one about 1.6 m tall, but not yet flowering. I have seen another three large flowering specimens in our immediate vicinity.

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