Stigmaria ficoides

The underground rooting structure of a scale tree such as Lepidodendron. The regularly spaced circular pits over the surface are the scars where fine rootlets attached.

Stigmaria is a form genus — a name for the root alone. Roots are usually found separated from any trunk, and much the same root structure was produced by several different scale trees, so it cannot be tied to one species.

Because these roots stayed where the tree grew, Stigmaria in place is good evidence of a fossil soil rather than transported debris.