The Lycosphens of Maryland, Delaware and the District of Columbia

Modern classifications of plants divide the vascular cryptogams into four classes: Psilopsida, Lycopsida, Sphenopsida and Pteropsida (in part). The second and third of these are often called the “lycosphens”, the first not being represented in the floras of temperate regions except in laboratories and hot houses and the fourth being the true ferns and fern-like plants; also included in the Pteropsida are the flowering plants and the gymnosperms. Under older classifications the first three classes and that part of the Pteropsida including the ferns were placed under the Pteridophyta, chiefly because of similarities in their life-cycles. This paper deals with the Lycopsida (Lycopodium, Selaginella and Isoetes) and the Sphenopsida (Equisetum).