No town of any consequence impedes the GRR’s 90-mile leg along the southern tip of Illinois. The roadside landscape continues to be fields of heat-loving corn and leafy soybean, while the bluffs of the Shawnee National Forest appear to the east. Much of the forested uplands are a botanical crossroads: glacier-borne northern species like the sumac and partridge berry; warmth-seeking southern species like the short-leaf pine; eastern species held back by the Mississippi, such as Virginia willow and silver bell; and western species with a toehold in the east, like Missouri primrose and Ozark coneflower. All count southern Illinois as the edge of their natural ranges. When John James Audubon passed through this region in the early 1800s, he recorded seeing thousands of bright green, red, and yellow-striped parakeets, but these birds are all long extinct.