I agree with floral_uk; it does look like loosestrife. here in Oregon is is a noxious weed that carries disease. Without being able to see it up close, it's tough to be sure. It is a possibility that it might be Epilobium (fire weed), but the shape of the inflorescence leads me to believe it's Lythrum salicaria.

link IDd as an invasive Lythrum salicaria (purple loosestrife). .. in the perennial forum ken

Jerzeegirl, it may be a Giant Dutchman's pipevine but I'd guess littoralis Elegans. Love their flowers. If the flowers are a foot long or more, it's definitely a Giant. Elegans flowers are about the size of your open hand. And, as Sharon said, pipevine swallowtails love pipevine. But, and I may be wrong, while pipevine swallowtails will lay their eggs on Giant Dutchman's pipevine, the plant is too toxic for the caterpillars and they will die. Pipevine swallowtails can use pretty much any pipevine except Giant. When I was in north central Florida the pipevine swallowtails used the native pipevine that grew wild on my property. However, Polydamas aka Goldrim swallowtails use Giant, Elegans and other pipevines as host plants. I've raised tons of Polydamas using Elegans. This swallowtail is pretty common here in SW Florida. Here's a few pics I took to help you identify them. Sorry that I don't have a picture of the butterfly from above but it's black with a gold band across the hind wings. Good luck!

There's a dedicated plant identification forum here on garden web. Name That Plant Forum. It's frequented by humans who have proved far more accurate than any app. Meanwhile, have a look at Cyanchum rossicum. Since you're in NE USA that could be it. And it's not something you want. But please post on NTP. You'll get a lot more answers there.