Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Plant Protection submitted time 2018-07-18 Cooperative journals: 《广西植物》
Abstract： The Plagiogyria is isolated in the classification system, an so far no reports about the systematic and comparative study of its anatomical structure have been published. The anatomical comparative study of the petiole and the pinnule cross-sections of 9 species of Plagiogyria was performed using light microscopy for the first time. The epidermis, the basic tissue and the middle column of the middle petiole transection and the epidermis, mesophyll and main vein of the vegetative leaf pinnule of 9 species of Plagiogyria are similar, for example, the epidermis of the transverse section of the middle petiole is not covered with hair or squamas, the epidermis is round in shape with thick-walled tissue, and the central cylinder is a amphicribral vascular bundle; the stomatas of trophyll pinnule transection are only distributed in the lower epidermis, the shape of epidermal cells is flat, and the type of the main vein belongs to the peripheral vascular bundle, which supports for the viewpoint that Plagiogyria is a natural taxonomy. In the evolution of the system, the Plagiogyria has a certain relationship with the Alsophila spinulosa and both of them have similar characteristics and also show certain differences. However, the petiole central transverse section of 9 species of Plagiogyria are trapezoidal, oval or triangular. The shape of the vascular bundle including "U" shape, "V" shape or triangle. The number of vascular bundles in the central transverse section of the petiole is one or three. The arrangement of xylem in vascular bundles including "Eight" shape, "U" shape or " 一" shape; The underside protuberances of the pinnule main veins are curved, triangular or trapezoidal. The xylem of the petiole has two forms: typical hippocampus and atypical hippocampus. The typical hippocampus is characterized by obvious hooks state at both ends of the xylem. The atypical hippocampus is characterized by no obvious hook state at the two ends of xylem or one of the xylems has no hook at one end. These morphological anatomical features are stable and cluster specific, providing a new reference for taxonomy and systematic studies of Plagiogyria. Finally, a key to the Plagiogyria species is given based on the anatomical characteristics of the transverse section of the petiole and the pinnule.
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