Anatomical structures of vegetative organs of Keteleeria fortunei (Murr.)Carr.var. cyclolepis (Flous) Silba and its ecological adaptability

In this paper, the anatomical structures of the roots, stems, and leaves of Keteleeria fortunei (Murr.)Carr.var. cyclolepis (Flous) Silba were observed by paraffin-sectioning and optical microscopy to analyze the adaptability of its morphological structure to the environment. Results showed that the leaves of K. fortunei var. cyclolepis were bifacial, including an 11.5 μm thick upper epidermis (outer layer covered by 4.5 μm cuticle) and an 8.6 μm thick lower epidermis (outer layer covered by 2.4 μm cuticle). Stomata were observed on the surface of the lower epidermis. There were 1-2 layers of cells in the palisade tissue and 3-4 layers of cells in the spongy tissue. There was a single, 474.1 μm thick main vein. In the primary structure of the stem, there were 1-2 layers of epidermal cells, 4-6 layers of outer cortical cells, 6-8 layers of endothelial cells, and resin ducts distributed in the inner cortex. In the secondary structure of the stem, there were 2-3 layers of cork cells and 1-2 layers of phelloderm cells. There were resin ducts and secretory cavities in the cortex, and vascular bundles were closely arranged in a ring. In the primary structure of the roots, there were three layers of cells in the exodermis and 1-2 layers of endothelial cells, with a Casparian strip. There were four types of primary xylem in the roots. In the secondary structure of the roots, there were 3-4 layers of cork cells and 2-3 layers of phelloderm cells. Thus, the anatomical structure of the vegetative organs showed great plasticity, which may account for the adaptive ability of this species to the sunlit as well as shaded environments, and its tolerance to both drought and cold.