The ferns are an ancient lineage of plants, dating back to at least the There are also two groups now extinct: Stauropteridales (with only two described genera from the Carboniferous)

Members of this group have relatively primitive morphology for ferns in that there is poor distinction between stem and leaf tissue, and leaves were not flattened into a single plane and did not produce a blade. Curious small appendages called aphlebiae occur at each branching point on the plants.

The vascular tissue within the stem and leaves was usually a solid core, or protostele, which was sometimes divided into four lobes in Stauropteris. Most species are believed to have been small and "bushy".

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Stauropterid Reconstructions : The habit and overall appearance of stauropterid ferns have been reconstructed from permineralized material. On the left is Gillespia randolphensis; on the right is Stauropteris ????.

The stauropterid ferns were previously classified in the Coenopteridales, a grab-bag assemblage of extinct eusporangiate ferns. Most of the species once included in that group have since been reclassified as leptosporangiates, leaving only the stauropterids and zygopterids. Each of these two remaining groups have since been formally recognized as orders.

For more information on fern relationships, visit the Filicopsida page on the Tree of Life.

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E. M. Gifford & A. S. Foster. 1988. Morphology and Evolution of Vascular Plants, 3rd ed. W. H. Freeman and Company, New York.

Taylor & Taylor.