Morpho-Anatomical Characterization of the Raisin Tree, Hovenia dulcis Thunb., Utilizing Optical Light and Scanning Electron Microscopy With Energy Dispersive X-Ray Spectroscopy.

Hovenia dulcis Thunb. (Rhamnaceae), known as the Chinese or Japanese raisin tree, is a medicinal plant widely used in Traditional Chinese Medicine, with all plant organs traditionally employed for therapeutic purposes. However, morpho-anatomical standards for authentication and quality control of its raw materials remain limited. This study investigated the morpho-anatomy of vegetative and reproductive organs of H. dulcis using light microscopy and scanning electron microscopy (SEM). Morphologically, the species presents glossy, glabrous leaves, a fleshy peduncle, dry capsular fruits, and seeds with a linear hilum. Anatomically, the stem shows a narrow, continuous ring of sclerenchyma surrounding the vascular cylinder. Leaves are homogenous with atypical palisade mesophyll, hypostomatic, and anomocytic and actinocytic stomata, and display marginal extrafloral nectaries. The edible fleshy peduncle contains a cylindrical vascular bundle and numerous amyloplasts. Flowers present a perigynous hypanthium and an inferior ovary with anatropous ovules. Seeds are oblong-elliptic, oily, and albuminous. Mucilaginous cavities occur in all organs except roots and seeds, and several types of inorganic crystals with distinct morphology and composition were observed in tissues. These anatomical and micromorphological traits provide useful parameters for the authentication and quality control of H. dulcis raw materials and contribute to systematic studies within the Rhamnaceae family.