The Structure, Differentiation And Evolution Of The Seedlings Of Some Angiosperms

Seedling is an important stage in the ontogeny of angiosperm. And its anatomical features are importantly significant on the ontogeny and systematic evolution. As follows are the primary results:1. The development on the seedling of the Salsala collina pall, was studied. The results included that single Kranz structure and diphasic chloroplast are found in the photosynthetic structure of seminal leaf and true leaf ;the secondary leaf vein is antitropous radiant parallel vein; the stomatal apparatus arranges longitudinal, but the long axis between guard cell and epidermal cell are vertical. The axial organoes such as stomatal apparatus ,photosynthetic tissue and vascular bunlde are activated simultaneously at the middle of the cotyledon-node zone. These characters indicate that the seedling of Salsala collina pall, are specific on anatomy feature.2. The comparative study in the structural difference between cotyledon and the true leaf of Papaver orientate L. seedling indicated that there is only a single vein in cotyledon during the process from the budding stage to the deciduous one, and the vein differentiated gradually from the axial CNZ to the apex of cotyledon, while there is multistage pinnate vein in the ture leaf ,and the connection of vascular system between the leaf base and CNZ, through de- and re-differentiation of parenchymatous cells in the upper part of CNZ, was later than the generating of the second lateral vein.The results support CNZ is primitive, further more ,the relation between single vein of cotyledon and microphyll was discussed. In addition,the study of comparative anatomy on the axial vascular system of Papaver orientate and Chelidonium majus L. applied that the vascular cylinder type in the lower part of CNZ of Papaver is circular diarch haplostele and the parenchymatous cells unexisted among the vessel elements,while the vessel elements in the lower part of CNZ of Chelidonium arranged twistedly, containing a lot of parenchymatous cells. The stele styles in the lower part of CNZ provides new evidence for the classification of the two genus.3. The studies focused on the CNZ Euphorbia hirta L. seedling applied regular triangle exarch haplostele, enriching the diversity of vascular cylinder in CNZ. Furthermore, the ontogenesis of primary vascular system was that the "regular triangle"exarch haplostele in the lower part of CNZ, elongated downwards to the root to format the tirarch exarch actinostele,then upward to the middle of CNZ to format the siphonostele, and finally to format the simple eustele.The spatial and temporal characteristics and the model of the ontogenesis of the primary vascular system recurs the systematic development.