The extinct tree genus that formed vast Carboniferous coal-swamp forests with scale-like bark was Lepidodendron.
Lepidodendron was not a modern tree in the botanical sense, but an arborescent lycophyte: a tree-sized relative of plants such as modern quillworts. During the Carboniferous, it grew in wet coal-forest ecosystems alongside other giant lycopsids, horsetails and seed plants. Some species reached about 40–50 metres, with trunks more than a metre wide.
Its nickname, “scale tree,” comes from the diamond-shaped leaf scars covering the trunk. The pattern was left when narrow, spirally arranged leaves fell away. Lepidodendron had relatively little true wood compared with modern trees; much of its mature stem consisted of supportive outer tissues. Cone-like reproductive structures called Lepidostrobus grew at branch tips.
The genus is often loosely called a giant club moss, but that comparison can mislead. Lepidodendron was more closely related to quillworts than to today’s club mosses. Calamites, another option, was a giant horsetail relative, while Glossopteris belonged to a very different seed-plant lineage associated especially with later Permian floras.