arrived in the area specified from somewhere else by any means (adjective); not native (non-indigenous) to the area in which it has been found. Various authors have used expressions alien

was first used by Bacon (1605), and more recently by Pemberton (1964). It is the exact complement of the word native

species are those that were introduced

(= "non-indigenous", arrived from somewhere else)

The expressions alien

(adj) not native and not fully established; locally or temporarily naturalized

In botany terminology, describes a plant which has been introduced to an area recently, in particular since colonisation by humans. (09 Oct 1997)

A species not intentionally introduced; growing here and there.

accidental adventitious (biology) Of a plant that is not native, but was introduced by humans to a place and has since become naturalized.

adventitious, or happening in one's life history in a unique way and not according to a universal system; see also imperative.