Ferns flourished in the Carboniferous and, while no longer a dominant group, they are still common around the world. Arborescent forms still exist, but most ferns are smaller. A large proportion of species are tropical, though nearly 100 species occur in California. The following table provides an overview of fern classification:

    The terms "eusporangiate" and "leptosporangiate" refer to details of the development of the sporangium in these two major lineages. From the information presented in the table, you can see that the fern lineage Polypodiales represents the vast majority of extant ferns. The classifications listed above are presented only as a reference for your information, as a framework for looking at fern diversity -- you won't be required to know the differences between eusporangiate and leptosporangiate ferns, or the details of fern classifications.

    The fern sporophyte usually has a rhizome, or underground stem, from which arise erect leaves. The figure at provides an overview of fern architecture and terminology.

    Sporangia are usually borne on the underside of the leaves, often in aggregations called sori (singular = sorus). The gametophyte is a small, free-living organism bearing antheridia and archegonia. For more information about fern biology and life cycle, go to Lab 11: Reproduction in Non-Seed Plants.

1. Compare the leaves (fronds) of ferns with those of the Lycophytes and Sphenophytes. How do they differ?
2. Compare the sporophyte with the gametophyte in terms of size and complexity.

Greenhouse fern	Greenhouse fern's sori	Tree ferns (Cyathea sp.) at Strybing Arboretum	Sori of Cyathea

 

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