- DIVISION: Tracheophyta
- CLASS: Magnoliopsida
- ORDER: Caryophyllales
- FAMILY: Cactaceae
- GENERA: Disocactus, Epiphyllum, Pseudorhipsalis, Selenicereus
Epiphyllums go largely unnoticed during much of the year, their unassuming, leaf-like stems biding time and gathering energy. But when spring arrives, an unforgettable show begins! In April and May, these tropical plants burst into their full glory, with large, jewel-toned blossoms that are anything but wallflowers. Actually, the term epiphyllum can mean two things. Epiphyllum—in italics, with a capital "E"—is a genus of cactus that includes about 19 species. The term "epiphyllum"—with lowercase "e"—as well as the term "epiphyllum hybrid" refer to hybrids of various cactuses in the genera Disocactus, Pseudorhipsalis, and Selenicereus (and less commonly, Epiphyllum). What these cactuses have in common is that they are all epiphytes—plants that grow on another plant without harming it. Epiphyllums are sometimes called orchid cactus, a reference to their epiphytic lifestyle and their spectacular blossoms. Some people call them "jungle cactus," because of the way they grow, dangling from trees in Central and South American rain forests.
Epiphyllums take root in the hollows and forks of a tree. Rain and humidity provide moisture, and decaying leaf litter and rotting wood provide nutrients. Some species grow erect, and others sprawl, vine-like. Without the sharp spines in other cactuses, epiphyllums have no leaves. Instead, the long, flattened stems take over the job of photosynthesis, producing energy from sunlight. Their claim to fame, though, is the size and splendor of their flowers, which sprout directly from the stems. Ranging in size from 1 to 12 inches (2.5 to 30.5 centimeters) across, epiphyllum blooms come in brilliant reds, creamy whites, deep oranges, bold yellows, and tantalizing pinks and purples.
For the most part, epiphyllums like moisture, mild temperatures, filtered sunlight, and light, porous soil. Unless you live where the climate is just right, they do best as houseplants or in greenhouses. They flower in late winter through early summer. There are thousands of different hybrid epiphyllum varieties.
According to the IUCN, several species of epiphyllums are vulnerable or endangered. With the exception of some artificially propagated hybrids, international trade in epiphyllums, as in other cactuses, is restricted by CITES. Loss of rain forest habitat—due to agriculture, logging, and mining—is a major threat to these unique plants.
The Safari Park's Epiphyllum House, open only select days in the spring, is a beautiful tribute to these surprising cactuses, created and maintained by dedicated volunteers of the San Diego Epiphyllum Society. It displays almost 600 plants, with names like "Sparkling Burgundy," "Candy Barr," '"Ice Follies," "Obsidian Queen," and "Greek god."