Stunning vistas of water-loving purple flowers may be steeping young American toads in poison.

Amphibian populations are in trouble all over the world, and one element in their decline could be invasive plant species such as purple loosestrife, a Cornell University researcher, Bernd Blossey, told 300 participants at an Ohio invasive plant conference.

Research on a number of invasive plants revealed harmful effects on not only American toads but spotted salamanders, red-backed salamanders and gray tree toads.

Loosestrife, native to Europe, is probably the most familiar of these invading plants across much of North America. It is high in tannin, a chemical that affects toads by interrupting digestion.

Phragmites, another invasive water plant common along the Lake Erie shoreline, is poison to some salamander species. And gray tree frogs are hurt by an invader known as Japanese knotweed.