Original article adaptive leaf anatomical characteristics of Lysimachia vietnamensis and Lysimachia insignis in Yen Thuan commune, Cham Chu nature Reserve, Tuyen Quang province

Abstract

This study investigates the leaf anatomical characteristics of two species, Lysimachia vietnamensis L.K. Phan & C.M. Hu and Lysimachia insignis Hemsl., based on specimens collected from Yen Thuan commune, Cham Chu Nature Reserve (Tuyen Quang province), with the aim of clarifying their adaptations to different ecological conditions. The results indicate that L. vietnamensis, which occurs at elevations above 700 m, exhibits well-developed palisade tissue, a distinct protective cuticle layer, high stomatal density (SD: 142 stomata/mm²), and a high stomatal index (SI: 22.76%). These features reflect a strong capacity for gas exchange and adaptation to high-light environments. In contrast, L. insignis, which grows under forest canopy at lower elevations, possesses palisade tissue composed of short, nearly rounded cells, along with lower stomatal density (60 stomata/mm²) and a lower stomatal index (SI: 6.31%), indicating adaptation to shaded and humid conditions. The differences in leaf anatomical structure between the two species clearly demonstrate adaptive divergence in response to elevation and light intensity, providing a scientific basis for taxonomy, conservation, and ecological restoration applications.