A perennial grain is a grain crop that lives and remains productive for two or more years, rather than growing for only one season before harvest, like most grains and annual crops. While many fruit, nut and forage crops are long-lived perennial plants, all major grain crops presently used in large-scale agriculture are annuals or short-lived perennials grown as annuals. Scientists from several nations have argued that perennial versions of today's grain crops could be developed and that these perennial grains could make grain agriculture more sustainable.