FIG. 33.11 Diversity of ferns and horsetails. (a) The adder’s tongue fern Ophioglossum, (b) the whisk fern Psilotum, (c) the horsetail Equisetum, (d) a marattioid fern, (e) an aquatic fern (Salvinia), and (f) a polypod fern (in the middle of the photo is Athyrium felix-femina, the common lady-fern).

Photo sources: a. Jonathan Buckley/age fotostock; b. Biophoto Associates/Science Source; c. CuboImages srl/Alamy; d. Courtesy Gary Higgins; e. FLPA/Chris Mattison/age fotostock; f. Ron Watts/First Light/Corbis.