In a california woodland a mistletoe plant gets its nutrition from live oaks, thus weakening the oaks, what kind of symbiosis is expressed in that relationship

Parasitism is the kind of symbiosis expressed in that relationship. Parasitism is a type of symbiotic relationship between two organisms where one is usually harmed and the other gets benefits from the relationship. From the question, the mistletoe plant benefits from the relationship by getting its nutrition from live oaks, while the live oaks are harmed. This type of relationship between the two organisms is called parasitism.