Fig. 2

Evolution of flowering pathway networks in embryophytes. a Cladogram of embryophyte divisions highlighting the estimated evolutionary origin of flowering pathways during earth history. The embryophyte cladogram is plotted over the Phanerozoic (541–0 million years), and the recorded presence or absence of flowering pathway modules is indicated by plus or minus signs, respectively. A question mark indicates that no studies on flowering pathway modules are available yet. b Simplified flowering regulatory pathway network. The color code refers to the proposed evolutionary origin. The age-dependent pathway (blue) might be of Paleozoic origin as some of its components are conserved throughout all land plant divisions. The photoperiod pathway (green) probably evolved in the Mesozoic as homologs of florigen-encoding genes originated after angiosperms and gymnosperms separated. Vernalization pathways (brown) originated in the temperate Cenozoic as global cooling of the earth occurred only approximately 50 million years ago when land plant families had already separated. Myr million years