Epiphyllum

Epiphyllum, commonly known as the orchid cacti, is a genus of broad, flat-stemmed cacti native to the tropical forests of the Americas, from Mexico through Central America and into South America. Unlike the desert cacti most people picture, these are true forest epiphytes that clamber through trees, prized for their spectacular, often enormous flowers and for being the backbone of countless garden hybrids sold under the name "epiphyllum" or simply "epi".

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Botanically the genus is fairly small, but in horticulture the name has spread to cover a huge range of large-flowered hybrids, many of which actually carry blood from related genera such as Disocactus, Selenicereus and Heliocereus. When a grower talks about their "epis", they almost always mean these showy hybrid plants rather than the pure species.

Description

Epiphyllum are shrubby, sprawling or pendent cacti whose stems do the work that leaves do in other plants. The stems are long, flattened and strap-like — sometimes cylindrical near the woody base — with scalloped or notched margins. Areoles are borne in these notches, and it is from them that both new growth and flowers emerge. Mature plants are spineless or nearly so, a reflection of their sheltered forest life rather than open desert.

The flowers are the main event. They are typically large, funnel-shaped and richly scented, and in many species open at night and last only a day or two. Wild-species blooms are often white or cream, while the garden hybrids have been bred into a dazzling range of pinks, reds, oranges, yellows and bicolours, some day-flowering. Blooms can reach an impressive size, and a well-grown plant in full flower is one of the most striking sights in cactus growing.

Distribution

The genus ranges through the humid tropics and subtropics of the Americas, from Mexico and Central America down through the Caribbean and into northern South America. Plants grow as epiphytes in the canopy and on mossy branches, or occasionally as lithophytes on rocks, rooting in pockets of leaf litter and organic debris rather than in true soil. This forest origin shapes everything about how they like to be grown: dappled light, steady moisture, good air movement and free drainage around the roots.

Notable species

Epiphyllum oxypetalum — the "Queen of the Night" or Dutchman's pipe cactus, famous for huge, fragrant white flowers that open for a single night; one of the most widely grown species.
Epiphyllum hookeri — a robust species with large white nocturnal blooms, often seen in older collections.
Epiphyllum anguliger — the fishbone or zig-zag cactus, grown as much for its deeply lobed, ric-rac stems as for its scented flowers.
Epiphyllum crenatum — an unusual day-flowering species and an important parent behind many coloured garden hybrids.
Epiphyllum phyllanthus — a widespread species with long, slender flowers.

Cultivation

Epiphyllum are among the easier cacti for a beginner precisely because they don't want desert treatment. Grow them in a chunky, well-drained but organic-rich mix — an epiphyte or orchid-style blend with bark and grit suits them far better than a pure mineral cactus mix. Bright, filtered light is ideal; direct midday sun scorches and yellows the stems, while deep shade gives lush growth but few flowers.

Water more generously than you would a globular desert cactus, keeping the mix lightly moist through the growing season and easing off in winter — but never let the roots sit in stagnant water (see Watering). A cool, drier rest in winter, with good light, helps trigger the flush of buds in spring. Feed lightly while in active growth, and favour a low-nitrogen feed as buds form to encourage flowering rather than leaf-like stem growth. These are naturally trailing plants, so a hanging basket or a pot near a bright window shows them off well and gives the long stems somewhere to cascade. Keep them frost-free; most resent temperatures near freezing. Once buds appear, avoid moving or rotating the plant, as sudden changes in light direction can cause bud drop. Repot every few years when the plant becomes top-heavy or the mix breaks down (see Repotting).

Propagation

Orchid cacti are famously easy from cuttings. A section of mature stem, allowed to callus for a few days and then set in a gritty, open mix, will usually root readily — this is how nearly all named hybrids are kept true, since seedlings do not come true to the parent (see Propagation — cuttings). Species can also be raised from seed, though seed-grown plants are slower and variable. Hybridising is a popular hobby in its own right: crossing two named plants and raising the seedlings in hope of a new flower colour or form is part of what makes the epiphyllum world so large and enthusiastic.

Hybrids and cultivars

The great majority of plants sold as "epiphyllums" are hybrids rather than pure species, and many are intergeneric crosses involving Disocactus and other relatives. Breeders have produced thousands of named cultivars, selected chiefly for flower colour, size and form, and dedicated societies maintain registers of them. When buying, it is worth remembering that a plant labelled only "Epiphyllum hybrid" could be almost anything in terms of parentage — but the care is broadly the same across the group.

Common problems

Few or no flowers — usually too little light, too much nitrogen, or no cool winter rest; mature plants that are slightly pot-bound tend to bloom best.
Bud drop — often caused by moving the plant, erratic watering, or a sudden change in conditions once buds have set.
Rot — soft, translucent, collapsing stems from overwatering or a mix that stays too wet; improve drainage and airflow.
Pests — mealybugs, scale and spider mites are the usual offenders; see Pests and diseases.

References

Horticultural information for growing these plants as ornamentals. Always confirm plant identification and any handling, grafting, or safety advice against authoritative sources before acting.