How did DNA studies change the classification of Cucurbitales plants?

Before the advent of DNA studies, the classification of the order Cucurbitales was based primarily on morphological characteristics, which often led to uncertain or incorrect placements of its constituent families. Molecular analysis transformed this understanding by providing more robust, testable data that frequently conflicted with older, morphology-based schemes like the Cronquist system.12

Key changes driven by DNA evidence include:

• Reclassification of Families: DNA studies clarified the relationships of families that were previously misplaced. For example, Coriariaceae was once linked to Ranunculaceae due to its separate carpels, and Anisophylleaceae was formerly associated with Rhizophoraceae.
• Resolution of Uncertainties: Families like Corynocarpaceae, which long held an uncertain position, were integrated into the order based on molecular findings.1
• Distinguishing Convergence: DNA evidence helped botanists distinguish between true evolutionary relationships and similarities caused by evolutionary convergence, such as the superficial resemblance between some Anisophylleaceae and Cunoniaceae flowers.1

These findings were incorporated into the Angiosperm Phylogeny Group (APG) system, which organizes plants based on monophyletic lineages.2