LATHYRUS, in botany, a genus of the diadelphia decandria class. The stylus is plain, villous above, and broader below; and the two superior laciniæ of the calix are shorter than the others. There are 21 species, seven of them natives of Britain; viz. the pifolia or crimson grass-vetch; the yellow vetchling; the hirsutus, or rough-codded chickling-vetch; the latifolius, or broad-leaved pease-everlasting; the sylvestris, or narrow-leaved pease-everlasting; the palustris, or marsh chickling vetch; and the pratensis, or common yellow vetchling.