Stomatal size and density variation in riparian Araceae along gradient of the Samin River, Central Java, Indonesia

Abstract. Wulandari AA, Revalitha AA, Azzam AK, Allobua BSN, Rifki AN, Setyawan AD. 2025. Stomatal size and density variation in riparian Araceae along gradient of the Samin River, Central Java, Indonesia. Cell Biol Dev 9: 78-90. The riparian zone is a transitional area between aquatic and terrestrial ecosystems, playing a crucial ecological role as a buffer for water quality and as a habitat for biodiversity. The Samin River, located in Central Java, Indonesia, experiences varying abiotic conditions from its upstream to downstream regions, which can influence the biodiversity along its flow. This study aims to assess the diversity of species and the morpho-anatomical characteristics of stomata in plants belonging to the Araceae family across different sections of the Samin River, including the upstream, middle, and downstream areas. Leaf samples were collected through purposive sampling and were analyzed using the replica method to examine stomatal characteristics, such as location, type, shape of guard cells, number of adjacent cells, and stomatal index. A total of 6 species of Araceae were recorded, with species composition changing along the river continuum; only Xanthosoma sagittifolium occurred across all reaches and thus enabled within-species comparisons. Stomatal traits in X. sagittifolium showed a coordinated shift along the gradient, characterized by smaller stomata accompanied by higher stomatal number and density toward downstream sites. These patterns are consistent with epidermal plasticity and a stomatal size-density trade-off under contrasting environmental conditions across riparian reaches. Overall, the results highlight stomatal traits as sensitive cellular indicators for detecting environmental variation in riparian systems.