Comparative Study of Petal Micromorphology between Pueraria lobata and the Herbal Medicine Puerariae Flos (Fabaceae)

Background: Pueraria lobata (Willd.) Ohwi is traditionally recognized as the botanical source of the herbal medicine Puerariae Flos. However, adulteration in commercial markets necessitates reliable diagnostic criteria. This study presents the first comparative investigations of the petal epidermal micromorphology of wild P. lobata and commercial Puerariae Flos using scanning electron microscopy. Methods and Results: Fresh petals and commercial samples were prepared using standard fixation, dehydration, critical point drying, and platinum coating. Epidermal characteristics of standard, wing, and keel petals were examined on both surfaces. Both P. lobata and Puerariae Flos samples exhibited papillose cells on the standard and wing petals, as well as tabular cells on the keel petals, consistent with patterns in Fabaceae. However, distinct differences were observed in papillose cell types. P. lobata predominantly showed papillose conical cells, whereas commercial samples displayed papillose knobby cells. In addition, a transition from papillose conical cells to tabular rugose cells along the wing petal was observed in P. lobata. This transition was absent in commercial samples. Conclusions: These findings suggest that some commercial Puerariae Flos may originate from taxa other than P. lobata and provide useful candidate diagnostic features for identification and quality control. Nevertheless, further studies with broader sampling are necessary to confirm their consistency and taxonomic significance.