After Williamson, William C., A Monograph on the Morphology and Histology of Stigmaria Ficoides, 
1887, p. 13. Click Here for Full Size Image.

Note that in the drawing above there are no visible traces of roots even though the tree is sitting atop a laminated Fireclay and clays are supposed to be very good at preserving all sorts of (once living) things: Like (purportedly) 17 "million-year-old" fresh-looking, green and pliable  magnolia leaves.