The trees are assigned to the genus Lepidodendron, one of a number of lycopods of Carboniferous age and related to today’s small club mosses. These are often referred to as ‘scale-trees’ – so called because of the scale-like markings left on the trunk and branches when leaves fell off.
A piece of Lepidodendron bark from the Fossil Grove showing the diamond-shaped leaf-scars.
The root system, referred to as Stigmaria, have a characteristic bifurcating pattern; each main root divides into two and then these also divide into two and so on. When the surface is preserved they are characterised by circular scars where ‘rootlets’ were attached.
Stigmaria root with rootlet scars (photo courtesy Wikipedia)