haustorium

noun

1. A root of a parasitic plant modified to take nourishment from its host.

   “In the substomatal chamber all the signals that regulate the interaction between fungus and host are present along the entire structure of the rust fungus, from the vesicle to the first haustorium which, in the dikaryotic stage, is the first intracellular structure (Mendgen et al., 1988; Heath, 1989, 1995).”

2. A cellular structure, growing into or around another structure to absorb water or nutrients, such as a cotyledon.