What is "archaeophyte"

n. Any plant which was introduced to an area by humans (or arrived naturally, but from an area in which it was present as a human introduction) and became naturalised before 1500 (C.E.) (but especially in prehistoric times)

An archaeophyte is a plant species which is non-native to a geographical region, but which was an introduced species in "ancient" times, rather than being a modern introduction. Those arriving after are called neophytes. In Britain, archaeophytes are considered to be those species first introduced prior to 1492, when Christopher Columbus arrived in the New World and the Columbian Exchange began.