Hydrocotyle bonariensis Comm. ex Lam. (largeleaf pennywort, Araliaceae) is native to the Mississippi Gulf Coast. Its native range is from Argentina to North Carolina, and it is an ecological indicator in coastal areas including estuaries, sand dunes brackish wetlands, riparian habitats, and more. However, a population consisting of over two hundred individuals exist in Bolivar County, MS by a clay-rich ditch bordering the Bear Pen Park softball field. Hydrocotyle bonariensis has an underground rhizome; round, orbicular leaves with rounded scalloped serrations, and an umbel inflorescence, which may possess several levels of pedicels. Leaf petioles are slender and attached in the center of the leaf lamina. The flowers are greenish-white and are approximately 2-3 mm in size. Anatomical observations for this plant species have not been described previously. Using fresh samples, anatomical observations and cell measurements on stems, roots, leaves, and inflorescence components were completed. Single-edged razor blades and hand-held microtomes were used in preparing thin-sections. Prepared slides were stained with neutral red, safranin, or toluene blue. Digital photographs were taken using an Olympus BX43 microscope with an attached Q-color 3 camera. A JEOL scanning electron microscope was used to analyze petiole and leaf epidermal sections as well. Thirty-five measurements were taken on major cell components: parenchyma in petiole, pedicel, rhizome and peduncle; collenchyma in petiole and peduncle; guard cells on the abaxial and adaxial leaf surfaces; and more. Several cell types had a significant size range: cortex parenchyma (length 29 - 70 μm and width 20 - 81 μm), pedicel epidermal cells (length 8 - 20 μm and width 8 -22 μm) and subsidiary cells on the leaf adaxial surface (length 8 - 45 μm, width 16 - 46 μm). Significant anatomical features include amphistomatic stomata, arrangement of vascular bundles in the petiole (seven in a ring and one in the center), prolate pollen, absence of collenchyma in upper areas of the peduncle and pedicels. Future research includes making cross-sections of roots and leaves using a microtome to discern how it differs from other species in the Araliaceae.