adventive
/ədˈvɛntɪv/adjective
1That comes from outside or from some external source; extrinsically added; extraneous; foreign.
2 Ecology. Originally: (of a plant) occurring in a region in which it is not native, but imperfectly naturalized, e.g. restricted to cultivated land, areas around human habitation, etc. In later use also: (of a plant or animal) occurring in but not native to the region in which it appears.
3 Botany. Designating an embryo which develops asexually from a somatic cell of the ovule (e.g. the nucellus) as a result of a form of apomixis which occurs in certain plants.
noun
Ecology. An adventive plant or animal.
Origin
Early 17th century; earliest use found in Francis Bacon (1561–1626), lord chancellor, politician, and philosopher. From post-classical Latin adventivus (of a dowry) not derived from parents, of foreign origin from classical Latin advent-, past participial stem of advenīre + -īvus. Compare Middle French, French adventif.