Medullosa Stellata
Chemnitz, Germany

This is a seed fern seen in cross section. Those of the Medullosaceae family, like spore ferns, peripherally have leaf bases and rootlets, but unlike spore ferns, have medullary pith rays extending outwardly from the center in wedge-like formations as seen in this image. Centrally, where pith is usually found, the fern's vascular bundles are encapsulated by a structure that appears to have evolved from the vascular elements themselves.
Copyright © 2003 Giraud Foster & Norman Barker