[lemonad]

Not an answer to parent comments, just wanted to emphasize that coming from "somewhere else" <=/=> invasive. Not an expert so there are likely edge cases but one example would be a meadow where many different plants grow, flowering from early spring to late autumn. Introducing a new plant could mean it finds its own niche in this system or could mean that it completely takes over the whole system, reducing the overall flowering period to a limited time and thus causing problems for pollinators. If the latter is the typical result, the plant would likely become classed as invasive.