Stomatal anatomical variation of water hyacinth (Pontederia crassipes) across Bengawan Solo Oxbow Environments, Indonesia

Abstract. Zagoto JR, Febrisa KN, Mahmudah IR, Qanita IM, Rifki AN, Setyawan AD. 2025. Stomatal anatomical variation of water hyacinth (Pontederia crassipes) across Bengawan Solo Oxbow Environments, Indonesia. Cell Biol Dev 9: 99-112. Oxbow lakes formed along large tropical rivers represent heterogeneous lentic habitats that can impose contrasting environmental conditions on aquatic macrophytes. This study examined stomatal anatomical variation of water hyacinth (Pontederia crassipes) across three Bengawan Solo Oxbow Environments in Central Java, Indonesia, and evaluated how these anatomical traits relate to supporting physiological and growth indicators. Stomatal characteristics were quantified using a leaf-impression method on adaxial and abaxial leaf surfaces, while environmental parameters were measured in situ. Chlorophyll status was assessed using a Soil Plant Analysis Development (SPAD) Index, and plant performance was evaluated through dry biomass measurement. Across all oxbows, P. crassipes exhibited an amphistomatous leaf condition with anomocytic stomatal complexes, indicating a conserved stomatal structural pattern consistent with its free-floating growth form. Within this shared framework, quantitative variation in stomatal size and density distinguished oxbow environments. Tangkisan showed the highest stomatal densities on both leaf surfaces, whereas Kadokan exhibited the lowest values, with Sidowarno occupying an intermediate position. SPAD chlorophyll index and dry weight also differed among oxbows but did not correspond directly with stomatal traits, demonstrating that physiological status and biomass accumulation are influenced by multiple interacting environmental factors rather than stomatal anatomy alone. By integrating stomatal anatomy with SPAD and biomass measurements, this study highlights stomatal traits as robust anatomical indicators of environmental context in oxbow habitats, while emphasizing the role of physiological and growth metrics as supporting, not primary, indicators. The findings provide an anatomically grounded framework for comparative assessment of plant-habitat interactions in heterogeneous oxbow environments and underscore the potential of stomatal anatomy as a practical, field-relevant tool for evaluating habitat assessment in tropical river systems.