An heirloom vegetable is a cultivar that was commonly grown during earlier periods in human history, but which is not used in modern large-scale agriculture. Many heirloom vegetables have kept their traits through open pollination (non-hybrid) and they are untreated. The trend of growing heirloom plants in gardens has been growing in popularity in the United States over the last decade. The vast majority of these vegetable seeds are heirloom varieties.