Three very unwise men

Three men sharing accommodation decided to make a fresh vegetable salad, and the oldest convinced his junior flatmates that a plant growing in the back garden was Russian comfrey. Having made the salad the senior member ate three mouthfuls of the salad and then desisted because of the disagreeable taste. The second ate only one mouthful, and the junior member ate little at all because of the unpleasant taste. The two senior members started to feel ill within six …