Houndstongue, a plant native to Europe and Asia, has become prevalent in much of the United States, Canada, and other parts of the world. While its unique funnel-shaped flowers may attract attention, the plant is known for its annoying seeds, which can cling to animals and humans, causing irritation. Beyond its physical discomfort, houndstongue also produces pyrrolizidine alkaloids (PAs), toxic compounds that can damage the liver and other organs in herbivores and even humans. Despite its negative aspects, the efficacy of houndstongue’s defenses has contributed to its successful invasion of various regions.