The Angiosperm Phylogeny Group (APG) is an informal international collaboration of botanists who work together to produce a shared view of the taxonomy of flowering plants. Their goal is to arrange classification so it corresponds to evolutionary relationships and to reach a common consensus among specialists. The group places emphasis on classifications that reflect phylogeny, meaning groups should represent actual lines of descent.
History and versions
The APG first published a widely noted classification in 1998. Subsequent updates were released in 2003, 2009 and 2016, commonly referred to as APG I, II, III and IV. Each update incorporated new evidence and discussion among contributing authors; APG IV (2016) is the latest formal version produced by the group.
Approach
Rather than relying solely on traditional morphological traits, the APG system is largely informed by molecular phylogenetic studies, especially DNA sequence data, interpreted alongside morphology and other lines of evidence. The group aims to identify and classify monophyletic groups—those that include an ancestor and all its descendants—so that the resulting taxonomy reflects evolutionary history as closely as current evidence allows.
Effects and use
- The APG classifications have influenced modern treatments of angiosperm relationships in floras, checklists, databases and educational resources.
- Adoption of the APG framework has led to revisions in the circumscription and placement of many orders and families to better match reconstructed evolutionary trees.
- Because the APG is collaborative and evidence-driven, its proposals are often used as a starting point for regional and taxon-specific classifications.
Notes
Earlier classification systems for flowering plants often included groups that are not monophyletic. The APG's emphasis on phylogenetic support represents a shift toward classifications that aim to be hypothesis-driven and testable as new data become available.