Rhubarb is very commonly used in both European and Chinese medicine, especially the roots. It’s a strong purgative and laxative, though in smaller doses it’s an astringent tonic to the digestive system. Its leaves are toxic. Rheum palmatum is generally used, though garden rhubarb has similar properties.
The Rhubarb triangle is an area near Wakefield where most of the UK’s forced rhubarb is grown.