Lepidodendrales (from Gr. "scale tree") were primitive, vascular, arborescent (tree-like) plants related to the lycopsids (club mosses). They thrived during the Carboniferous period, and some reached heights of over 30 meters, with trunks often more than one meter in diameter. Sometimes called "giant club mosses", they are in fact more closely related to quillworts than to club mosses.