Study on Vessel Morphological Characteristics and Environmental Adaptability of 10 Gentianaceae Species From the Qinghai-Xizang Plateau.

This study employed scanning electron microscopy (SEM) to conduct a morphological observation of vessel elements from 10 Gentianaceae species collected on the Qinghai-Xizang Plateau. We systematically compared vessel type, end-wall and lateral-wall characteristics, and vessel diameter to explore their adaptive relationship to the extreme plateau environment and the evolutionary trends of vessels. The results indicated that the vessel end walls of all 10 species featured simple perforation plates, while annular, spiral, and scalariform thickenings were observed on the lateral walls of all species, with scalariform vessels constituting the highest proportion in most. The vessel types were primarily annular, spiral, and scalariform; pitted vessels were found only in Gentiana farreri and G. waltonii. The vessel diameters were generally small (mostly < 20 μm). The vessel morphology exhibited significant adaptive characteristics to plateau adversities such as low temperature, drought, and intense radiation. Based on the analysis of vessel type, end wall features, and lateral wall characteristics, the vessels of G. farreri and G. waltonii exhibited the highest proportions of morphologically specialized types (pitted and scalariform vessels) according to the classical Bailey-Frost sequence, whereas those of G. aristata and G. hexaphylla were dominated by the more generalized annular and spiral types. This research provides new anatomical evidence for understanding the structural adaptation mechanisms of Gentianaceae plants in high-altitude environments and offers a theoretical basis for the conservation and utilization of these plant resources.