Lathyrus niger, also known as black pea, blackening flat pea and black bitter vetch, is a perennial legume that is native to Europe. Its common name is reference to the blackening of the plant's foliage as it dies. The seeds of the species are not to be confused with edible 'black peas', which are a form of Pisum sativum. Seeds of Lathyrus species are toxic, containing an enzyme that interferes with collagen synthesis to cause the disease Lathyrism.