Division Lycophyta

These plants are commonly known as the lower ferns and possess true vascularized stems, leaves and roots. The position and microanatomy of the vascular tissue is characteristic of these forms. The leaves are described as microphylls, i.e. enations or reductions of the stem in which the vascular strand is simple, a trace, a single vein. The spore producing bodies are on special branches and the structure is known as a "strobilus". The sporangia which contain the spores are associated with fertile leaves known as sporophylls. During the Carboniferous Period of geological time this group was represented by some of the largest and most numerous plants.

The Division Lycophyta is composed of the following:
Order Lycopodiales (Clubmosses)

There are many living and extinct forms known. The Order possesses one type of spore (homosporous) from which one gametophyte produces antheridia and archegonia and the sperm cells possess two flagella. Primary growth, dichotomous branching, and lack of ligules (tapered structures at the base of leaves) are also characters. There are no tree-like forms in extant species. The term, club mosses, is used for the Order Lycopodiales or just for the Genus, Lycopodium. The genus is large containing some 180 species.

Order Selaginellales (Spikemosses)

There are living and extinct forms but only one third as many as the Lycopodiales. This Order possesses 1) ligules, the tapered structures at the base of leaves, and 2) two types of spores (heterosporous), microspores and megaspores, which give rise to male and female gametophytes and sperm cells with two flagella. The development of the gametophytes is described to be "endosporic", a character peculiar to the spikemosses and the quillworts.

Order Isoetales (Quillworts)

Although the Isoetales possess some characteristics that are similiar to the Selaginellales: 1) presence of ligules, the tapered structures at the base of leaves, and 2) heterosporous spores which are endosporic, there are characters peculiar to their Order alone. Their microphyllous leaves grow from a short tuberous stem known as a "corm" which possesses unusual secondary growth and their sperm cells are multiflagellate.