Lepidodendron is the name assigned to this ancient lycopod, also known as the "scale tree" because of the distintive diamond-shaped leaf scars that covered it's outer bark midsection.
It was prolific during the Carboniferous Period (360 to 286 million years ago) and capable of achieving gigantic size, growing to heights of more than 130 feet with supporting trunks measuring up to 6 feet or more in diameter.
Modern descendents are tiny dwarfs by comparison-- including varieties of the herbaceous ground or club mosses (Lycopodium), quillworts (Isoetes), and spikemosses (Selaginella)
Reconstruction of Lepidodendron
(Drawn by Jerry Jenkins after various sources)
From: Plant Fossils of West Virginia, Educational Series ED-3A
West Virginia Geological and Economic Survey- 1978
William H. Gillespie
John A. Clendening
Hermann W. Pfefferkorn