Research the seed surface of Rheum wittrockii Lundstr. from the flora of Kazakhstan

Rheum wittrockii Lundstr. is a rare and endangered species endemic to the mountainous regions of southeastern Kazakhstan. Despite its ecological importance and conservation status, no detailed investigation of its seed micromorphology has previously been conducted. This study addresses this gap by providing the first comprehensive characterization of the seed surface of R. wittrockii using scanning electron microscopy (SEM). Seeds from three geographically distinct natural populations were analyzed. The results revealed a distinctive combination of micro morphological traits, including a densely reticulate-tuberculate testa, irregular epidermal cells with undulate anticlinal walls, a relatively thick multilayered seed coat, and filamentous outgrowths potentially aiding in dispersal and anchorage. Morphometric measurements were largely consistent across populations, with minor intraspecific variations related to local microhabitat conditions. Comparative analysis with related species (R. altaicum, R. tataricum, R. palmatum, and R. officinale) confirmed the unique taxonomic position of R. wittrockii, supported by its distinct seed surface architecture. These morphological features likely represent ecological adaptations to arid, high-altitude environments, enhancing desiccation resistance and seed longevity. Overall, the findings contribute to improved taxonomic resolution within the genus Rheum and provide valuable insights for the conservation of this narrowly distributed and ecologically specialized species.