The grass pea (Lathyrus sativus), also called chickling vetch, khesari or guaya, is the small, angular seed of a hardy annual climbing legume — one of the most drought- and flood-tolerant of all food crops, grown across the drylands of South Asia, the Horn of Africa and the Mediterranean as a famine-insurance pulse. Cheap, protein-rich and able to yield where almost nothing else will, it carries one grave shadow: heavy, prolonged eating of the seed can cause neurolathyrism, an irreversible paralysis of the legs traced to the neurotoxic amino acid β-ODAP.