Haustorium

In botany and mycology, a haustorium (plural haustoria) is the appendage or portion of a parasitic fungus (the hyphal tip) or of the root of a parasitic plant (such as the broomrape family or mistletoe) that penetrates the host's tissue and draws nutrients from it. Haustoria penetrate the host plant's cell wall and siphon nutrients from the space between the cell wall and plasma membrane but do not penetrate the plant's cell membrane itself.