Bitter vetch (Lathyrus montanus) belongs to the Fabaceae (the Pea family). it is a perennial herb that is native to Europe. This herb grows in pastures, woods and scrubs, usually on acid soils, to 2200 m elevation. The stems are winged and can reach 15-45 cm in height. The leaves are impari-pinnate with 2-4 pairs of linear or elliptic leaflets. The flowers are crimson and turning greenish-blue gradually, and they bloom from April to June. The fruits are hairless, red brown pods.