The non-flowering ferns were the dominant plants of the Paleozoic world, but with climate change they were gradually edged out of this role by the gymnosperms and then the flowering plants, which are better adapted to dry climatic conditions. Eventually, the ferns were relegated to the forest floor.
不開花的蕨類曾是古生代地球上植物的「主流」，隨著氣候變化，漸遭裸子植物、開花植物取代，終於退居森林底層。