Comparative Leaf Anatomy Of The Family Polygonaceae In Shandong Province

China is located in the north temperate zone; it is an important part of the angiospermsbirthplaces. Polygonaceae, which is a large herb branch of the angiosperms mainly produced inthe the north temperate zone, is one of the important groups to explore the origin and evolutionof angiosperm. Polygonaceae belongs to Polygonales of Dianthus subclass; its maindistinguishing features are the membranous sheath, alternate single leaf and so on. Scholarsfrom many countries used various methods such as morphology, anatomy, cytology,phytochemistry, molecular systematics and geographical distribution to do detailed researcheson Polygonaceae and its following groups. They proposed different classification systems orrevision of the original system. According to different methods the results are often different.Taken together, there are several questiones: Confine of the tribe Polygoneae; the scope of thePolygonum s. lat.; Classification status of some species and infra species and so on.Although comparison of leaf anatomy occupies an important position in the classificationsystem, there has been no systematic study reported in the domestic academic world. Thepurpose of this experiment is to explore the relationship between the groups of plants from thePolygonaceae family by way of the continuous comparative anatomical study on the petiolesand veins, in order to be able to provide some of the more valuable taxonomic evidence toresolve some taxonomic exist differences. Using conventional paraffin sections, the authorstudied28species and2varieties plants of the Polygonaceae in Shandong province frompetiole to leaf blade. Through careful observation of the anatomical pictures, the leafcharacteristics of each species, from the vascular system, fundamental tissue system to dermaltissue system, were given detailed descriptions including identify features. Based on the resultfrom the study of the variability of the characters at different taxonomic levels, the charactersbelow were selected to be used at sectional and generic levels. All the descriptions of theanatomical groups were restricted to characters as follows:（1）The distal vascular (larger vascular): number, the vascular at the bottom is whether thelargest or not.（2）The adaxial vascular (or a combination of vasculars): number; position; whether constant.（3）The vascular bundles of the leaf central vein.（4）The bundle sheath: outer sheath clear or not, inner sheath of sclerenchyma or not.（5）Xylem and phloem: the shape and level of development.（6）Collenchyma:location and the type.（7）Aerenchyma: location and the type. （8）Assimilating tissue:location and the type.（9）Extrafloral nectary: have or have not, location and type.（10）Epidermal trichome: location and the type.The characters of petiole and leaf anatomy can be used to define the scope of the materialsas follow:（1）Define the scope of Atraphaxidead: Calligonum, Atraphaxis, Parapteropyrum andPolygonum s. str.; Rumex and Rumiceae are polyphyletic groups.（2）Sect. Polygonum upgraded to Polygonum s. str.; sect. Persicaria upgraded to Persicaria;sect. Bistorta upgraded to Bistorta; sect. Cephalophilon upgraded to Cephalophilon;Polygonum sibiricum upgraded to Knorringia; Antenoron downgraded to sect. Antenoron.（3）support the status of sect. Aconogonon、sect. Fallopia and sect. Homalocladium.（4）Polygonum aviculare and Polygonum plebeium should belong to different sections;Polygonum chinense L. and Polygonum nepalense should belong to different sections;nonsupport to the status of P. lapathifolium var. salicifolium.From all these we provided some of the more valuable taxonomic evidence to resolve sometaxonomic exist differences in Polygonaceae. It is believed, that these anatomical evidence canbe applicable not only for Polygonaceae but also for angiosperms. And that remains to be seenin further experiments.