The majority of the Mazon Creek area plants, approximately 35 species, belong to the now
extinct but diverse group of plants known as seed ferns. They grew on higher ground away from
saturated, peaty subsoils. Some grew in a vine-like fashion, but most were arborescent, reaching
up to 35-feet in height. Despite the name, these are not closely related to true ferns, but bore
seeds like conifers and flowering plants.