Study On Leaf Anatomy And Embryology Of Helwingia Chinensis

Helwingia chinensis is an under-exploited plant with ornamental, culinary and medicinal values in theCornaceae family. This species garners widespread interest because its flowers and fruits in are unusallyattached to the leaf’s central vein. Combining field observations with optical microscopy of paraffin slices, Iconducted floral embryology and leaf anatomy studies on Helwingia chinensis. The results are as follows:(1) The experimental materials were obtained from Wuhan. Helwingia chinensis flowers appeared atthe end of March as buds, began to blossom in early April, and withered by mid-May.(2) Having differentiated from the nucellar epidermis, archesporial cells then divide to form periperalcells and sporogenous cells. The subepidermal sporogenous cell adjacent to the micropylar end developsdirectly into the megaspore mother cell. Integument tapetum and commitment bead plate appear duringovule development. The megaspore mother cell subsequently goes through two consecutive meioses,forming first a dyad and then a tetrad. The tetrad is arranged in a linear or a T-shaped fashion. The threemegaspores near the micropylar end udergo programmed cell death, leaving only the megaspore near thechalazal end functional. This megaspore proceeds to become the single-celled embryo sac, which furtherdivides into the mature embryo sac that contain7cells and8nuclei. Embryo sac development of HelwingiaChinensis Batal belongs to the polygonum type, with an inferior ovary, a single ovule integument, and anoverhanging placenta.(3) The anther parietal is formed by circumferential differentiation of protodermal andsubprotodermal cells, as well as parenchymal cells adjacent to the sporogenous cells. The primarysporogenous cells divide into the secondary sporogenous cell, which becomes the microspore mother cell with a typical simultaneous cytokinesis. The mature pollen grain is2-celled with3colpi.(4) The petiole of Helwingia chinensis shows the secondary structure of the dicotyledon stem. Thevascular tissue in the petiole is concentrated within a single bundle containing pith. The vascular bundlesplits into two parts along the medullary rays as it nears the base of the inflorescence, extending respectivelyinto the peduncle and the leaf’s central vein. The inflorescence is attached to the median or basal stretch ofthe leaf’s central vein.(5) Floral embryonic development of Helwingia chinensis is similar to that of Cornus officinalis.