LEPIDODENMRON (Neo-Lat., from Gk. 2_s ic, frpis, scale Oici5poc, dendrotl, tree). An important genus of extinct tree-like club mosses, the remains of which are abundant in rocks of Carboniferous age in many parts of the world. These plants. sonic of which grew to trees 75 to 100 feet in height, were gigantic ancestors of the modern club-mosses (Lycopo dium), with which they have many points of re semblance. They grew in abundance in the swampy forests of Carboniferous coal-measure time, and their trunks, stems, leaves, and cones contributed largely to the vegetable mass which has been hardened into coal. They were stout tree, with high woody trunks and central pith, and slender branches that bore closely set strap shaped or awl-shaped leaves, and at the ends of the branches were borne large cone-like fruc tifications (Lepidostrobus) comparable to those of the club-mosses, hut much larger. Their well known roots have been called Stigmaria, which name is also applied to the roots of other Car boniferous plants. Lepidodendrons may he rec ognized by the form and arrangement of the scars left on the trunks and stems by the fallen lea yes. These scars are rhomboidal or diamond shaped in outline and are arranged diagonally to the axis of the ,tent. In this respect they dif fer from the scars of Sigillaria, which is often found associated with Lepidodendron, and which have a longitudinal arrangement parallel to the axis of the branch. Lepidodendron appears first
in the Lower Devonian rocks, was very abun dant in the coal-measures of Carboniferous time, and became extinct in the Permian period. Sev eral allied genera—Ulodendron. a tree-trunk from the Devonian; Lepidophloios-. Lomato phloios; and Knorria, represented by decorti cated stems in Permian rocks—are grouped to gether in the family Lepidodendriike, which is eminently characteristic of Upper Paleozoic for mations.
BIBLIOGRAPHY. SOIMS-LRIlbaCh, Fossil Botany Bibliography. SOIMS-LRIlbaCh, Fossil Botany (Oxford, 1S91) ; Lesquereux. "Description of the Coal Flora of the Carboniferous Formation in Pennsylvania, and Throughout the United States," in Sf+ond Geological Surrey of Penn s! lrania, Report of Progress—P, vols. i., ii., and v. Illarrisburg, ISSO-84) ; Williamson, ization of the Fossil Plants of the Coal Measures, part ills, Lycopodiacere, Lepidodendrex. Sigil larke." in Philosophical Transaetious (London. 1S72) ; David White. "Fossil Flora of the Lower Coal Measures of Missouri." in Monograph of the United States Geological Surrey, vol. xxxvii. (Washington. 1S99) ; Zittel, Schimper, and Bar rois. Trait(' de paltontologie. part ii., Pab'ophy tologic (Paris, Munich. and Leipzig, 1S91).