Created by a farmer who wished to make his fortune growing it barren lands, Wild Wheat is barely edible (for humans) but extremely common, and considered an invasive species by many farmers. A land covered in Wild Wheat is commonly known as a Wheatland.
Wild Wheat is certainly not native to the coastal areas, but it can tolerate both occasional seawater and nutrient barren soils, enabling it to grow all along the shore.
Fast-Wheat is a variant of wheat that is extra fast growing but much less resilient to competition from other species. It was made by some genius or another several thousand years ago, who decided to fix the barren patches without killing everything else off, too. Its also occasionally creates unusually durable seeds, capable of surviving dormant for centuries.
Fast-Wheat is rather common on recently barren patches in one region, where farmers keep it stored in granaries. It is also common on a few islands, where almost nothing else currently lives. However, it has died off everywhere else, killed off by the less edible Wild Wheat.
Some researchers argue that Wild Wheat was originally Fast-Wheat, but a farmer objected to his free wheat-fields dying off as soon as native grasses started seeding the area. Others claim that they are independant species.