Stigmaria Fossil Root of Lycopsid Tree

Description: Stigmaria is a form genus for tree roots of Carboniferous coal forest Lycopod trees such as Sigillaria and Lepidodendron.

Lycopodiophyta appear in the fossil record in the Silurian in conjunction with many other vascular plants, and led to the trees that would dominate the equitorial landscape in the Mississipian and Pennsylvanian periods. North America was at the equator during the Carboniferous (290 to 359 million years ago). There were extensive, hot and swampy forests with Pteridospermatophyta (seed ferns) and huge Lycopodiophyta trees, Sigillaria and Lepidodendron, some on the order of 30 meters tall with trunks a meter or more thick. Unlike modern trees, lycopid tree leaves grew along the full extent of the trunk and branches, falling off as the plant grew, leaving but a small cluster of leaves at the top. These forests became the coal seams we mine for fuel in moderm times; stigmaria are often impregnated with coal, or have coal sticking to their surface. Note the round nodes on the surface of this fossil, which is where small roots grew out in all radial directions.

This fossil comes from a very old collection, some 50 to 60 years old, which was the plant fossil collection of a man and wife team who combed more than 100 plant fossil sites, almost all west of the Mississippi River. No doubt, some of these sites have been subsumed by strip malls, and urban sprawl, or are otherwise no longer open to collecting. There was no Internet for these amature collectors to research their treasures, so many plant fossils were unidentified.