Anatomical structures of vegetative organs of Salvia sonchifolia C. Y. Wu and S.petrophila G. X. Hu, E. D. Liu & Yan Liu (Lamiaceae) and their ecological adaptability

In this paper, the vegetative organs of Salvia sonchifolia and S. petrophila were observed by paraffin-sectioning, optical microscopy, and scanning electron microscopy to analyze differences in anatomical structures and adaptability to the environment. Results showed that the leaf epidermis of both species was covered by trichomes and a cuticle, and stomata were only distributed in the lower epidermis. Anatomically, the thicknesses of the upper and lower epidermal cells, cuticle on the upper epidermis, palisade tissue, spongy tissue, and phloem and xylem in the midrib, as well as density of non-glandular hairs, were all significantly higher in S. petrophila than in S. sonchifolia. For primary roots, both species had diarch roots and S. petrophila had no pith. For secondary roots, both species contained periderm and secondary vascular tissue, of which the phloem accounted for a large proportion, and the parenchyma cells contained starch grains. The four corners of the stem contained thick collenchymas and large vascular bundles. These results indicated significant differences between the two species in the primary structure of the roots and anatomical structure of the leaves. The presence or absence of pith, number of palisade tissue layers of the leaf, and density of non-glandular hairs of the leaf can be used as diagnostic characters between the species. The anatomical structures of the vegetative organs of S. petrophila and S. sonchifolia were characteristic of adaptations to xeric environments. In contrast, cold and drought resistance was stronger in S. petrophila than in S. sonchifolia, while the latter was more suited to shaded and weak light environments.