The previous post (link) was about calendulas, called marigolds, now more properly called pot marigolds, important plants through much of European history. In the 1500s, a different group of flowers, species of the genus Tagetes (sunflower family, Asteraceae) were introduced to the Old World from the Americas. People loved them, called them marigolds and presently they became the plants people recognized as marigolds, not the Eurasian calendulas.
Marigolds, Tagetes, were not wildflowers when they were brought to Europe (by 1520). The Aztecs and other Native American groups had been growing them for centuries.
Marigolds and calendulas are mixed up in the literature (previous post). Both are plants with yellow to orange flowers in the sunflower family, Asteraceae. Calendulas, Calendula officialis, are from southern Europe or the Near East, and over the last 1000 years were called marigolds or pot marigolds in the European literature. Marigolds, species of Tagetes, are native to the New World and were introduced to the Old World in the 1500s. Lacking English names originally, they were initially called French marigold (Tagetes patula) and African marigold (Tagetes erecta) in England. Today the Tagetes species are generally called marigolds and the calendulas (pot marigolds) are much less well known.