The Stanger Formation is a geological formation located in Kansas, United States. It is known for its abundant plant fossils, which provide valuable insights into the flora of the region during the Late Pennsylvanian epoch, approximately 307 to 300 million years ago.

The plant fossils found in the Stanger Formation include a variety of ferns, lycopods, and horsetails. These plants were likely growing in a swampy environment, as evidenced by the presence of other fossils such as freshwater clams and snails.