The Arrow Arum plant was named "Macopin" by the Indians of Macoupin county. It was a root which they gathered from the marshes. The women pulled the roots up from the ground at the bottom of the water which could sometimes be waist high. They were poisonous when raw, but once cooked they were roasted or ground using the flour to make bread, which was a main staple in their diet.
This name was also given to the main water stream that ran through the county.