Strangler ivy was a term used to describe a type of climbing vine plant lifeform which could overwhelm and potentially kill whatever other plant it attached itself to. Several types of ivy behaved in this manner, as well as other plants that were not technically ivies (such as kudzu).
Dr. Elizabeth Lense compared the Ardanan parasite which infected Crewman Fabian Stevens's brain to a strangler ivy, because of the long tendrils it extended into different parts of his brain, overwhelming its functions. (CoE eBook: Signs from Heaven)