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Plant adaptation to external pressures depends on functional diversity in cytochrome P450 (CYP) enzymes. CYPs contain structural domains necessary for the characteristic P450 fold that allows monooxygenation, but they also have great variation in substrate binding affinity. Plant genomes typically contain hundreds of CYPs that contribute to essential functions and species-specific metabolism. The CYP72A subfamily is conserved in angiosperms but its contribution to physiological functions is largely unknown. With genomic information available for many plants, a focused analysis of CYP subfamily diversity is important to understand the contributions of these enzymes to plant evolution. This study examines the extent to which independent gene duplication and evolution have contributed to structural diversification of CYP72A enzymes in different plant lineages. CYP72A genes are prevalent across angiosperms, but the number of genes within each genome varies greatly. The prevalence of CYP72As suggest that the last common ancestor of flowering plants contained a CYP72A sequence, but gene duplication and retention has varied greatly for this CYP subfamily. Sequence comparisons show that CYP72As are involved in species-specific metabolic functions in some plants while there is likely functional conservation between closely related species. Analysis of structural and functional domains within groups of CYP72As reveals clade-specific residues that contribute to functional constraints within subsets of CYP72As. This study provides a phylogenetic framework that allows comparisons of structural features within subsets of the CYP72A subfamily. We examined a large number of sequences from a broad collection of plant species to detect patterns of functional conservation across the subfamily. The evolutionary relationships between CYPs in plant genomes are an important component in understanding the evolution of biochemical diversity in plants.