In the mists of my memory, I have a recollection of a quote about man putting the secret of life in his pants, forgetting, and sitting on it. For some reason, thinking about invasive plants brings that to mind. All these invasives were brought here deliberately, usually for agriculture. I wouldn't be surprised if garlic mustard arrived on the continent before the colonies. There were lots of Europeans here before Jamestown and Plymouth. They came seasonally to fish, mine, and lumber. I bet they planted gardens. And garlic mustard was a likely seed contaminant, if not a crop. These days the USDA and similar groups try to warn us, and ban invasives. But that only happens after the fact, and often after they've recommended a species. But we do have many wise people, like these who are on their way from pulling garlic mustard in the Preserve. Are you part of the tribe that weeds the skunk cabbage patch? It's amazing how many there are!