C₄ pathway was first reported in members of Family Gramineae (grasses) like sugarcane, maize, sorghum, etc. In C₄ plants, PEPCo (PEP carboxylase) is the key enzyme used to fix CO₂ in C₄ plants.Oxaloacetic acid is a 4-C compound and is the first stable product so this pathway is known as C₄ cycle.