Soapwort or Sweet William is endemic to Europe and its range extends to Western Siberia. Acquired its Soapwort common name by alluding to the toxic substance saponin, which starts foaming when gets in contact with water and can be used in washing and cleaning things.
Saponins it contains have expectorant and laxative effect but if overdosed may cause nausea, diarrhoea and vomiting. Despite of its potential toxicity it is used as an emulsifier in the tahini halva and in brewing to create beer with a good “head”.
In India the rhizome is used as a lactation inducer.