Systematic Significance Study On Gametophyte Development Of Pteris L.

In this paper, The subject investigated is 12 species of Pteris L.. The research adopts the methods of aseptic culture and conventional culture. Observing and recording the whole process of the materials'sexual generation. Making a classification keys according to the types of spores germination, the ways of cell division in process of filament growing up to young prothallus, the growth patterns of prothallus, the shapes of adult prothallus, the characteristics of sexual organs and the shapes of border cell, et cetera.The growth patterns of materials such as P. setuloso-costulata Hayata, P. fauriei Hieron., P. esquirolii Christ, et cetera summarized as five types: A, B, C, D, E,. The development characteristics of type A: Spore germination is of the Vittaria-type. The apical cell of filament underwent longitudinal division that forms two-dimension development. Young prothallus is anisomerous Heart-like and the adult prothallus is symmetrical Heart-like (The characteristics above are typical development way of Ceratopteris-type). The development characteristics of type B: Spore germination is of the Vittaria-type. The apical cell of filament underwent longitudinal division that forms two-dimension development. Young prothallus is anisomerous Heart-like and the shape of adult prothallus like"∞". Two development lines above of prothallus have a little different in shape, which are main development methods in Pteris L.. Such as P. setuloso-costulata Hayata, P. tripartita Sw., P. ensiformis Burm. var. victoriae Bak., P. linearis Poir., P. excelsa Gaud., P. henryi Christ, P. wallichiana Agardh and P. semipinnata L. are all belong to these two methods. The development characteristics of type C: Spore germination is of the Vittaria-type. The apical cell of filament underwent oblique division that forms two-dimension development. The young prothallus were subcordate, and the adult prothallus were symmetrically cordate. Only P. fauriei Hieron., P. ensiformis Burm. belong to this type in the paper. The development characteristics of type D: Spore germination is of the Vittaria-type. The apical cell of filament underwent oblique division that forms two-dimension development. Young prothallus is anisomerous Heart-like and the adult prothallus is symmetrical Heart-like with splitting wings. Only P. vittata L. belong to this type in the paper. The development characteristics of type E: Spore germination is of the Vittaria-type. The apical cell of filament underwent oblique division that forms two-dimension development. Young prothallus is anisomerous Ribbon-like, adult prothallus is Branch-like or irregular type that between Heart-like and Strap-like. Only P. esquirolii Christ belong to this type in the paper.Comparing this research result with other reports, Pteris L. have a remote relationship with Hemionitidaceae, Adiantaceae and Dennstaedtiaceae, which belong to generalized Pteridaceae in the past. But the characteristics of gametophyte generation are similar to partial species of Vittariaceae and Sinopteridaceae. So it can be inferred that there may be a nearer relationship in systematic evolution among them.According to the laboratory results, the shape of border cell in the particular positon of gametophyte is stable, and there are differences among species. Border cell can be summarized as two types,"Smooth-type"and"Wave-type", which considered as a reliable judgement factor in fern systematics. In addition, the paper sums up a variety of prothallus Features such as rhizoids, sexual organs etc.. Analyzing and redefining some ill-defined morphological issues under lots of research.Besides, the experiment make 10 species of Pteris L. spores sowed in variety of adjusted medium MS, and select more suitable medium to the early development according to the spore germination rate and prothallus primitive fission rate. The results show that each spore has a different requirement to nutrient content in the early of development step even in the same genus.The paper observes the characteristics of gametophyte generation of 12 species in Pteris L.. Summarizes its development ways of the gametophyte generation. Discusses the systematic position and significance of Pteris L. in fern systematics. Chooses the suitable culture medium for materials and wish to offer reference to conserve and systematic research.