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Why does the Angiosperm Phylogeny Group system group plant families into orders?

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red garden rose — Rosales Red garden roses (*Rosa* hybrid). Whereas wild roses have only five petals, most hybrid varieties have been bred to produce numerous petals in a wide range of colours.

The Angiosperm Phylogeny Group (APG) system groups plant families into orders to organize the understanding of plant diversity based on evolutionary relationships.1

Rather than relying solely on morphological characteristics, the APG system utilizes phylogenetic data derived from molecular techniques, such as DNA sequencing, to determine how plants are related by descent from a common ancestor. By grouping families into orders, the system presumes that the included families are related and that the order itself is monophyletic—meaning all members are derived from a single common ancestor.12

This organizational structure provides a hierarchical framework that reflects the evolutionary lineages of angiosperms, allowing botanists to better classify the vast diversity of flowering plants based on robust, testable data rather than artificial or purely descriptive systems.12