Premise of the Study: Secondary xylem (wood) produced by a vascular cambium supports increased plant size and underpins
the most successful model of arborescence among tracheophytes. Woody plants established the extensive forest ecosystems
that dramatically changed the Earth’s biosphere. Secondary growth evolved in several lineages in the Devonian, but only two
occurrences have been reported previously from the Early Devonian. The evolutionary history and phylogeny of wood production
are poorly understood, and Early Devonian plants are key to illuminating them