Quite common among the larger trees were two varieties of club-mosses, also known as scale trees. They were cone-bearing evergreens with only slight resemblance to modern conifers. Instead of seeds they produced spores, a method of reproduction which is practiced among ferns. The trunks were marked from bottom to top with uniform patterns of cushions and scars indicating the points at which leaves were attached during the earlier stages of growth. In the Lepidodendrons the rows of scale-like cushions wind spirally upward while among the Sigillaria there is a vertical arrangement of leaf-scars which resemble the imprints of a seal, these impressions being in straight and parallel rows on a surface which may be either ribbed or smooth. The leaves of scale trees were stiff and slender, and arranged in grass-like tufts at the top. Calamites, related to our horsetail rushes, were somewhat smaller than the scale trees. Their trunks consisted of a thin, woody cylinder with a pithy interior, and were marked at intervals by nodes which gave them the “jointed” appearance of a bamboo stem. Leaves were arranged in circles around the nodes of main stem or branches. Spore-bearing cones appeared at the tips of the stems. [Illustration: Prehistoric Plants Some of the larger and better known plants of past ages are shown as reconstructed by artists. Finer details of the reconstructions often have to be neglected because of uncertainties due to the scattered and fragmentary character of the fossil record.] LEAF IMPRESSIONS Carboniferous Ferns Strap-leaf Conifer (Cordaites) MODERNIZED TYPES Sequoia Cone and foliage Miocene Fossils (Florissant Shales) Maple Willow Eocene palm (Denver Beds) HORSE TAIL RUSHES Restoration (Calamites) Fossils Leaves and Stem CYCADS Restoration Fossil Trunk CLUB MOSSES Restoration (Sigillaria) Fossils Trunk Impressions SCALE TREES Restoration (Lepidodendron) Fossil Leaf scars Also included among the larger trees were the Cordaites or large-leaved evergreens, tall and slender, seed-bearing but not true conifers as yet. Leaves were strap-shaped or grass-like, the larger ones having a length of six feet and a width of six inches. Trunks were woody, resembling pine, but with a central pith. The flowers were small and resembled catkins in form.