Most plants are autotrophic, meaning they produce their own energy and do not depend on other living things to obtain nutrients; they photosynthesize to generate their own energy and absorb water and nutrients from the soil. However, some plants rely on other plants for energy and nutrients and are called parasitic plants. Approximately 1% of flowering plants possess the ability to parasitize other plants. Initially, parasitic plants develop a structure called a haustorium, which attaches to the host plant. Next, the parasite connects its own pipe system, called vascular system, to that of the host (Fig. 3.1). Since vascular system is a network that transports water and nutrients, the fusion of the vascular systems of the parasite with that of the host enables the parasite to draw water and nutrients directly from the host. In this way, the parasitic plant extracts resources from its host much like a mosquito inserts its proboscis into a blood vessel to draw blood.