An invisible existence
Deep within the seasonally dry tropical forests of Morelos, an entire plant lives a life unseen. Bdallophytum americanum is a holoparasite, meaning it derives all of its water and nutrients from a host plant, completely abandoning photosynthesis. It has no leaves, no stem, and no true roots of its own. Its entire vegetative body exists as a network of filamentous threads, much like a fungal mycelium, that penetrates and spreads throughout the roots of its host. This internal system is known as an endophyte. For most of its life, B. americanum is completely invisible, its presence known only to the host trees, which are typically members of the genus Bursera—the same family as frankincense and myrrh.
The parasite's threads tap directly into the host's vascular system, primarily the phloem and secondary xylem, to siphon off the products of photosynthesis. This extreme adaptation to a parasitic lifestyle is so effective that the plant has shed all the typical features that would identify it as a flowering plant. For many years, its classification was uncertain. Botanists historically placed it and its relatives in the family Rafflesiaceae, alongside other bizarre, non-photosynthetic parasites like the famous corpse flower. This grouping was based on their shared, highly-reduced physical forms, a result of convergent evolution.