We will cover the other groups, which are of Mesozoic and Cenozoic importance, in a later lab. To begin our study of ferns, take a quick look at the variety of live ferns in the lab. Most of these are filicalean ferns, which show a variety of plant form and leaf morphologies. On each of them see if you can figure out what portions of the plant are leaf, stem, and root. Remember that many ferns have either underground or lateral-growing above ground rhizomes as stems, and leaves, or fronds can be large and elaborate.
Roots are adventitous and generally produced on the stem.
Some of the ferns may also have fertile leaves. The small aquatic ferns that may also be available in the lab represent the heterosporous water ferns, which belong to the orders Marsileales and Salvineales. Internally the stele is composed of numerous segments that sometimes appear to be surrounded by secondary xylem. Peripheral loops can sometimes be confused with the carnial canals of sphenopsids, but the peripheral loops are composed entirely of parenchyma and associated with a mesarch strand, while carnial canals represent the position of protoxylem that was destroyed during intercalary growth, in an axis characterized by endarch xylem maturation. Look at the photos that show examples of the Cladoxylales such as Cladoxylon and Pseudosporochnos.