The ornamental climbing plant whose seeds and pods contain the toxic saponin wisterin is wisteria.
Wisteria is a genus of woody vines in the legume family, Fabaceae. Its familiar drooping racemes of purple, blue, pink or white flowers make it a popular choice for pergolas, walls and arches. The same plants produce flattened, bean-like pods containing seeds that should not be eaten.
Wisterin is reported throughout the plant, including the bark, roots, pods and seeds. Ingestion can cause nausea, vomiting, abdominal pain and diarrhea; severe cases may lead to dehydration or collapse. Toxicity can vary among plant parts and species, and reports particularly emphasize the seeds and pods. This makes wisteria easy to mistake for a harmless ornamental legume.
The genus includes Chinese wisteria (Wisteria sinensis), Japanese wisteria (Wisteria floribunda) and American wisteria (Wisteria frutescens). Chinese wisteria reached Western horticulture in the early 19th century and can become invasive in parts of the eastern United States. Its beauty and vigorous growth should not be confused with edibility.