Sigillaria

Sigillaria is a lycopod fossil of the late Carboniferous and early Permian. They were typical coal forest trees similar to the "Lepidodendron". These swamp forest trees grew to 50 meters. They were anchored by an extensive network of branching underground roots. 
It was a lycopod, an early land plant. This was one of the trees which made up the Carboniferous coal-forests.
It had thin grasslike leaves that grew on the stem. The stem of the plant was green. Sigillaria reproduced with spores. It went extinct about 300 million years ago.