Ferns and Fern Allies

Abstract

The ferns and fern allies include the ferns, psilopsids, lycopsids, and horsetails (sphenopsids). These are seedless, vascular plants. They have an alternation of generations in which the sporophyte is dominant and has an axis containing xylem and phloem. (Further information concerning details of organ and tissue differentiation of vascular plants, with particular reference to seed plants, can be found in Salisbury and Parke, Vascular Plants: Form and Function, this series.) The ferns and fern allies differ from each other primarily in the pattern of organization of the plant body. A little of this diversity, with emphasis on contemporary representatives, is discussed in the following pages.