The Comparative Study On Morphological Characteristics Of Vessel Elements Of The Ribes

The Ribes is a genus with higher economic value while the morphological variations of it is amplitude. Because the characteristics of vessel elements of xylem have very vital significance on the taxonomy and phylogenetic, so the research on the xylem has an important position. In order to provide theoretical basis for the evolution of the genus light microscope and scanning electron microscopic were used to study morphological structure of vessel elements of29kinds of seven subgenus of Ribes.The main results are as follows:(1) The types of vessel elements of Ribes are pitted and threaded,and there are tails in all the seven subgenus.(2) The length and width of vessel elements with the tendency of increase with the increase of the age of branches.The length of vessel elements is250～440μm, and the diameter is15-30μm.(3) Perforated plate is scalariform perforation plate and the number of bars is5.2～11.0, with a small number of subgenus appering reticulate-scalariform, scalariform-simple transitional perforated plate, the angle of side walls is smaller and does not change a lot among species.(4) There are alternate pitting and both alternate pitting and opposite pitting,pit bordered,and the pit shape is some different.(5) There are lateral-wall perforation plates in R. odoratum, R.girdldii var. polyanthum and R.moupinense var. muliense. Generally speaking, the form of vessel elements of subgenus in Ribes is similar and further illustrated that the Ribes is a single department.The evolutionary relationships from the perspective of morphological characteristics of vessel elements in each subgenus of Ribes were analysed, inferring the following conclusion:subg. Symphocalyx, subg. Parilla, subg. Grossularia and subg. Berisia characterized with relatively evolutional characteristics; subg. Ribesia performance is the most primitive, subg. Coreosma and subg. Grossularioides are preliminary identified in the middle type.In addition, based on the comparison of morphological characteristics of vessel elements of Ribes, the relationship between morphological characteristics and ecological adaptability of the vessel elements was analysed. Researches showed that Ribes L. varieties under different habitats have strong correlation between morphological structure and its ecological adaptability. The results show that the vessel elements of hygrophilous species is shorter and wider in diameter,while the vessel element of the xerophytes species is longer and smaller in diameter and ones of mesial species are in the middle size in both length and diameter.