Lycopodiophyta - Classification

Classification

There are around 1,200 living (extant) species of Lycopodiophyta which are generally divided into three orders (Lycopodiales, Isoetales, and Selaginellales); in addition there are extinct groups. There is some variation in how the extant orders are grouped into classes: they may be put into a single class; they may be put into two classes, with the Isoetales and Selaginellales combined into one class; or they may be put into three classes, one order in each. The system which uses two classes for extant species is:

• Class Lycopodiopsida – clubmosses and firmosses
• Class Isoetopsida – quillworts, scale trees, and spikemosses
• Class † Zosterophyllopsida – extinct zosterophylls.

The following phylogram shows a likely relationship between Lycopodiophyta orders.