Sphenophyllales

An extinct group of articulate land plants, common during Late Pennsylvanian and Early Permian times. They are typified by Sphenophyllum, a small, branching plant, probably of trailing habit. The long, jointed stems had superposed, longitudinal, surficial ribs between nodes. The vascular system contained a solid xylem core with triangular primary wood. The leaves were wedge-shaped and had toothed, notched, or rounded distal margins. Long, terminal cones, when found detached, contained sporangia and spores. Most species were homosporous (produced spores of a single type). See also Paleobotany.