How did DNA sequencing change the classification of Alismatales and other flowering plants?

DNA sequencing has fundamentally transformed plant taxonomy by shifting classification from systems based on overall physical similarity to phylogenetic systems, which group plants by their evolutionary descent from common ancestors.1

In the case of orders like Alismatales and others, molecular evidence has provided a more objective tool for determining relationships than traditional comparative anatomy or embryology. By measuring the degree of similarity in DNA sequences, researchers can quantify how much different species have diverged since sharing a common ancestor. This approach has revealed that many groups previously thought to be related were not, leading to significant taxonomic rearrangements.2341

For example, in groups like Asparagales, DNA characters are now primary in defining families, as unique morphological features are often not obvious. Similarly, molecular data has challenged long-held assumptions about which plants are the most "primitive," such as reevaluating the basal position of Magnoliales within the angiosperm tree. Modern systems, such as the Angiosperm Phylogeny Group, continue to refine these classifications as more molecular evidence accumulates.41