Wheat
Wheat refers to an entire genus of grasses (Triticum) once domesticated as a staple crop. As the climate changed, though, it became harder and harder to grow wheat, even as the fossil fuels necessary to grow the crop in degraded soils became harder to come by, leading to the eventual abandonment of agriculture of all kinds, including growing wheat. Many varieties of feral wheat have developed in the centuries since, and several flourish across the Fifth World in the genus’s original ecological niche, as an early succession grass.