Annularia

Annularia is a form taxon, applied to fossil foliage belonging to extinct plants of the genus Calamites in the order Equisetales.

==Description== Annularia is a form taxon name given to leaves of Calamites. In that species, the leaves formed radiating leaf whorls at each stem node, in a similar way to the branches of Equisetum, an extant genus of horsetails. Annularia leaves are arranged in whorls of between 8 and 13 leaves. The leaf shape is quite variable, being oval in Annularia sphenophylloides and linear to lanceolate in Annularia radiata, but they are always flat and of varying lengths.