Tags: Fern.
Annularia is a plant fossil from the Carboniferous (around 360 to 300 million years ago). It is a form taxon. Its radiating structures are most like the leaves of Calamites. Annularia are the leaf whorls of an extinct horsetail. Their stems were also like the stem of Calamites. These horsetails Sphenopsida grew to a height of 32 feet(10 meters) in a tree-like form.[1]
