Comparative Morpho-Anatomical Structure of the Leaflet and Stem and its Initial Chemical Analysis of the <i>Tribulus</i> Species (Zygophyllaceae) from the South Central Coast of Vietnam

This article provides a comprehensive account of the morphology, micromorphology, and phytochemical composition of two Tribulus species in Vietnam, Tribulus cistoides L. and Tribulus terrestris L.. The study aims to describe and compare the morphological and anatomical characteristics, as well as phytochemical composition in the stems and leaves of the two species for potential applications in the pharmaceutical field, using the double-staining method and preliminary phytochemical screening based on characteristic reactions. The results show that T. cistoides and T. terrestris are similar in habitat, the oblong-lanceolate leaflets, the ovate-lanceolate stipules, but are distiguished by the flowers and fruits shape. Micromorphology, of both species is similar in the structrure of the midrib of the leaf (one upper and lower epidermis layer, palisade mesophyll, vascular bundles, sclerenchyma, parenchyma), the leaflet blade (dorsoventral with one upper, lower epidermis, palisade and spongy mesophyll, and vascular bundles with Kranz- type sheaths), and stem (one epidermis layer parenchymatous cortex, pericylic bundles, vascular bundles, and pith). It can be identified based on the xylem row count in leaflet vascular bundles, the spongy mesophyll of the leaf blades, and stem vascular bundle features. In the preliminary qualitative screening, both species were found to contain important compounds such as alkaloids, saponins, and flavonoids, with polyphenols, tannins, coumarins, quinones, terpenoids, amino acids, and carbohydrates being reported for the first time in T. cistoides. These findings support accurate identification and standardization of medicinal materials, conservation evaluation, and provide a foundation for future pharmacological and biological studies.