Lycopod

The Lycopods (Lycopodiophyta or Lycophyta) are the oldest surviving vascular plant division. This is a subdivision of the plant kingdom. Its earliest fossils are from 428–410 million years ago.p99
The Lycopods include some of the most primitive (basal) living species. They reproduce by shedding spores and have macroscopic alternation of generations. Members of Lycopodiophyta have a protostele, and the sporophyte generation is dominant.
Lycopods differ from all other vascular plants in having microphylls, leaves that have only a single vein rather than the much more complex megaphylls found in ferns and seed plants.
The first coalfields.
The lycopods, or club mosses, are the main plants in the Carboniferous rain forests. They were only partly eaten by insects and other life-forms. Mostly they formed swamplands which in the course of time became coal measures. In fact most of the coal from the Carboniferous period comes from these swamplands.
Classification.
There are around 1,200 living species of Lycopodiophyta; they are generally divided into three orders. There are also some extinct groups. There are different opinions as to how the whole group should be classified.p8 Living groups are: