外来的;非土长的
Adventive \Ad*ven"tive\, a. 1. Accidental. 2. (Bot.) Adventitious. --Gray. Adventive \Ad*ven"tive\, n. A thing or person coming from without; an immigrant. [R.] --Bacon.
adventive adj : not native and not fully established; locally or temporarily naturalized; "an adventive weed"