Anatomical structure of the vegetative organs of Calanthe tsoongiana and their ecological adaptation

The anatomical characteristics of the vegetative organs of Calanthe tsoongiana T.Tang et F. T. Wang were studied by paraffin sectioning to explore their ecological adaptation. Results showed that the leaf was isobilateral. Furthermore, compared with general plants, the leaves had less epidermal hair and fewer stomata, which were both distributed in the lower epidermis. The stomatal apparatus was slightly convex. The differentiation degree of the vascular bundles in the leaf was varied, and the xylem was much thicker than the phloem. The pseudobulb consisted of epidermis, ground tissue, and vascular bundles, and the ground tissue was well developed with abundant inclusions. The vascular bundles were scattered throughout the basic tissue. The root was mainly composed of the velamina, cortex, and stele. The velamina consisted of four layers of cells and the cortex was composed of 8-10 layers of parenchymal cells. The mycelium infected the cortex by destroying the velamina cells. The middle columnar channel cells were thickened on all sides, except the pericycle cells facing the xylem ridge. The vascular bundles were of radiative type and the pith, which was located in the center of the stele, consisted of parenchymal cells. Thus, the anatomical structures of the nutritive organs of C. tsoongiana showed features of a shade plant. Shade treatment and well-ventilated conditions should be provided in the processes of introduction and cultivation.