adventive

adj

1. Accidental.
2. (archaic)Adventitious.

   “For Hvmane Knovvledge, Which Concernes the mind, it hath two parts, the one that enquireth of The Svbstance, Or Natvre Of The Sovle Or Mind; The other, that enquireth of the Facvlties Or Fvnctions Thereof: vnto the firſt of theſe, the conſiderations of the Originall of the ſoule, whether it be Natiue or aduentiue; and how farre it is exempted from Lawes of Matter; […]”

3. Of a plant: not native, but introduced by humans to a place and since naturalized.

noun

1. A non-native plant that has become naturalized.

   “Such interlopers are known as exotics, adventives, or aliens, all terms that may be considered synonymous with "nasty.”