An example is rye, a common Mediterranean species. Rye was originally just a weed growing with wheat and barley. Weeding made it like the crop. Like wheat, it came to have larger seeds and more rigid spindles to which the seeds are attached. Rye is a tougher plant than wheat: it survives in harsher conditions. Having become a crop like the wheat, rye was able to become a crop plant in harsh areas, such as hills and mountains.