Fig. 7
From: Fossils and plant evolution: structural fingerprints and modularity in the evo-devo paradigm
Structural (anatomical) fingerprints (in black, at left) preserved in the secondary tissues of plants living and extinct provide evidence for specific component processes of vascular cambial growth (in purple, at left) and the activity of their corresponding regulatory modules. Different combinations of such fingerprints define the distinct modes of secondary growth that differentiate seed plants from extinct sphenophyllalean sphenopsids and zygopterid ferns