The primary difference lies in their botanical classification. The term "Epiphyllum" specifically refers to a genus within the Cactaceae family, comprising approximately 19 recognized species. These are true epiphytes, meaning they grow non-parasitically on other plants in their jungle habitats. In contrast, "other jungle cacti" is a broad horticultural term encompassing several distinct genera that share a similar epiphytic or lithophytic growth habit. Key genera include Schlumbergera (Christmas/Thanksgiving Cactus), Rhipsalis (Mistletoe Cactus), Hatiora (Easter Cactus), and Disocactus. Therefore, while all Epiphyllums are jungle cacti, not all jungle cacti are Epiphyllums.
Epiphyllum and its relatives are characterized by modified stems that perform photosynthesis, as their leaves are reduced to spines or are absent. However, the form of these stems varies significantly. Epiphyllum species are renowned for their large, flat, leaf-like stems that are typically lanceolate or oblong with serrated or scalloped margins. These stems are the plant's primary photosynthetic organs. Other jungle cacti exhibit a wider array of forms: Schlumbergera has flattened, segmented stems with rounded edges, Rhipsalis species often feature slender, pendulous, and sometimes angular or cylindrical stems, while Disocactus can have broad, trailing stems similar to Epiphyllum but often with more pronounced undulations.
The flowers present one of the most striking points of differentiation. True Epiphyllums produce spectacular, large, and often nocturnal flowers. They are funnel-shaped with multiple layers of petals and a prominent floral tube. Their blooms are typically white or cream, though hybrids offer a vast color range, and they emit a strong, sweet fragrance to attract nocturnal pollinators like moths. Conversely, other jungle cacti have distinct floral signatures. Schlumbergera flowers are day-blooming, zygomorphic (bilaterally symmetrical), and come in red, pink, white, or orange, with a more horizontal presentation. Rhipsalis flowers are generally much smaller, numerous, and bell-shaped, while Hatiora produces star-shaped, day-blooming flowers at the stem tips.
As cacti, all these plants possess areoles, the specialized structures from which spines, flowers, and new stems emerge. The configuration of these areoles is a key identifying feature. In Epiphyllum, the areoles are located in the notches or indentations along the stem margins (the serrations) and are often woolly. They may bear very short, bristle-like spines or be nearly spineless. In comparison, Schlumbergera areoles are found at the tips of the stem segments and at the joints between segments, typically bearing fine bristles or hair-like structures. Rhipsalis areoles can be scattered along the stems and are often very subtle, sometimes with minimal to no visible spines.
