LYCOPHYTES
Raven 7th, p. 380-389
Raven 8th, p. 403-412
Introduction
Lycophytes includes three families of vascular plants: the Lycopodiaceae, Selaginellaceae, and Isoetaceae. All of these plants have vascularized leaves, roots, and stems. The stems have exarch protostelic vascular tissue. They have their sporangia associated with leaves known as sporophylls. Selaginella and Isoetes are characterized by having ligules (tonguelike protuberances) on their leaves, whereas Lycopodium lacks these structures. In addition, Lycopodium is homosporous, whereas Selaginella and Isoetes are heterosporous. This is your first exposure to the concept of HOMOSPORY and HETEROSPORY … make sure you understand it well as it will come up again in defining each of the vascular plant groups covered in Biology 210.
