Practice question

APG IV system published 2016 revises classification using comprehensive plastid rbcL atpB matK ndhF and nuclear 18S gene matrices analyzed via maximum likelihood Bayesian inference, abandoning sole morphological reliance because floral characters highly homoplasious due to pollinator adaptation and convergence. Synapomorphies defined by molecular substitutions support monophyletic orders and families worldwide. Data sources include whole plastome sequencing, transcriptomics, revealing that Amborellales diverges first then Nymphaeales. Fossil record calibrates divergence times but not basis of group circumscription. Thus DNA sequence data provides primary criterion for family delimitation, improving stability compared to Cronquist morphology-based system previously dominant and artificial.