Abstract:

【Objective】 Bamboo leaf organs include vegetative (branches and leaves) and culm (culm sheath) leaves. To explore the relationship between vegetative leaves and culm sheaths, this study aimed to reveal the structural differences in different leaf organs of bamboo plants due to different functions, and provide new theoretical information for basic biological research on bamboo plants. 【Method】 This study used six bamboo species, namely, Dendrocalamus brandisii, Bambusa emeiensis, Lingnania intermedia, Chimonocalamus delicatus, Fargesia yunnanensis, and Phyllostachys mannii. The leaves, culm sheath, and leaf branches of six kinds of bamboo were used as experimental materials, differences in microstructure were observed, and their indexes were measured and compared. 【Result】 The anatomical structure of the leaves showed differentiation of finger arm cells or plum blossom-like cells in anatomical structure, and thin-walled vascular sheath cells were observed around vascular bundles. The sheath blades in the upper part of the culms were closer to the vegetative leaves in shape, whereas those in the lower part of the culms were shorter and thicker, with a thick cuticle and without apparent differentiation of mesophyll cells, which was significantly different from that of vegetative leaves. The ratio of phloem area to vascular bundle area of the leaf, petiole, leaf sheath and twigs was higher than that of xylem, which was significantly different from that of the culm sheath. The proportions of xylem area in vascular bundles of the culm sheath and culm sheath blades were higher, among which the sheath blades at the upper part of the culms were similar to the branch leaves in shape and size, but the proportion of xylem area in vascular bundles was higher. The anatomical structure of the leaf sheath and culm sheath was different from that of the leaf blade and sheath blade but was basically the same as that of the petiole. Moreover, the base of all branch sheaths or culm sheaths covered branches or axillary buds; therefore, it was considered that the sheaths should be a modified petiole. 【Conclusion】 The phloem was more developed in vegetative leaves, whereas the xylem was more developed in the culm sheath. This could be due to the fact that vegetative leaves mainly function in nutrient transport, whereas the culm sheath mainly functions in water transport. The cumulus sheath should be a modified petiole. In addition, the vascular bundles of all organs and tissues of bamboo showed that the phloem was in the adaxial direction of the vascular bundle, and the xylem was located in the adaxial direction of the vascular bundle.

Key words: bamboo, culm sheath, foliage leaf, anatomical structure, physiological function