Lepidodendron

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Lepidodendron (also known as the “Scale tree”) is an extinct genus of primitive, vascular, arborescent (tree-like) plant related to the Lycopsids (club mosses). It was part of the coal forest flora. They sometimes reached heights of over 30 metres (100 ft), and the trunks were often over 1 m (3.3 ft) in diameter, and thrived during the Carboniferous period. Sometimes called “giant club mosses”, this is actually not correct as they are actually closer to quillworts than to club mosses.

From Wikipedia