The Phactors have long had yellow flag iris (I. pseudacorus) as part of our gardens, and as Mrs. Phactor is the iris fancier, the fact that the yellow flag iris is an introduced species has never occurred to TPP, just never noticed. According to an article in the recent issue of the American Journal of Botany this non-native species can be do all the bad things that invasive species can do: in Louisiana wetlands it displaces native vegetation, it reduces biodiversity, and it degrades wetlands. The blue/purple iris is the native I. hexagona. Up here in Lincolnland, 800 or so miles upstream, the yellow flag is not known to be a problem. And the yellow flag probably got to N. America because someone thought it was purty. Oh, one of these days TPP will have to tell you about water hyacinth.