The orchid cactus is a gorgeous group of tree-growing flowering cactus plants. The Epiphyllum (the botanical name) has broad, flat, leaflike stems scalloped on the edge, strung together by a woody midvein.The Epiphyllum cactus are jewels and the proud owners of some of the largest, most unbelievable flowers in the whole plant world.The porcelain-petaled, saucer-size pond lily suffers by comparison.