Selenicereus chrysocardium

This epiphytic cactus exemplifies an evolutionary extreme within the cactus family. This species has descended from leafless stem succulents that had themselves descended from leafy shrubs, probably similar to pereskias. In the case of S. chrysocardium, it has evolved extravagantly leaf-like cladophylls from the sides of its stem segments as an adaptation to a humid and shady rainforest habitat. What is particularly fascinating is that the plant has had to create a makeshift "leaf" from a naked stem, having given up its true leaves during the course of its evolutionary history, and lacking the foresight to back-engineer the leaves that had devolved. This is a beautiful example of the types of ad-hoc structures one sees in nature that clearly show an absence of design within the evolutionary process.