Systematics Of Pseudocystopteris Ching

Pseudocystopteris was suggested as a new genus by Ching Ren-Chang in 1964 in light of Cystopteris spinulosa Maxim, which grows in northeast of China. Because the rhizoma late repente has few scales, the basal of petiole is not inflated spindle and does not become tapemess downward, the soris is round growing in later anteriore venularum, indusium is circle reniform or reniform, the basal pinnae never shorten and is often the longest. Consequently, Pseudocystopteris was separated from Athyrium and the systematical position is between Cystopteris and Athyrium. But Kato (1977) and Iron &Tron (1982) did not support his viewpoint and they claimed that Pseudocystopteris should be classified in Athyrium. Sano (2000) and Wang Ma-li (2003) found that Pseudocystopteris and the member of Athyrium belong to the same branch based on the molecule evolutionary-tree, and agreed with the latter. Many features of Pseudocystopteris, Cystopteris, and Athyrium were investigated systematically in this paper, including morphology of spore, leaf epidermis, tracheary elements, the anatomy character of scale and petiole, so that the systematical position of Pseudocystopteris can be determined.1 Morphological research of sporeThis three genuses share the same exterior morphology of spore, the spore is ellipse from polar sight and bean shape from equator sight. The surface ornamentation of perine of Pseudocystopteris has irregular lophate folds, with some joined into reticulate. The surface ornamentation of perine of Athyrium is divided into two types: one is ornate, the other is similar to Pseudocystopteris, and also has irregular lophatefolds. The surface ornamentation of perine of Cystopteris obviously different from those of the two former genuses is echinate. The number of clitellum in Pseudocystopteris and Athyrium is between 13 and 14, while that is above 15 in Cystopteris.2 Research of leaf epidermis characterIn Pseudocystopteris and Athyrium, the shape of up epidermis are sinuate, the shape of up epidermis of Cystopteris is irregular concaveconvex. As for the stomatal style, there are five types, such as axillocytic type, polocytic type, anomotetracytic type, anomocytic and copolocytic type. The axillocytic type is the main pattern in Pseudocystopteris and Athyrium, which both have polocytic type and copolocytic type. But, anomotetracytic type is the main pattern in Cystopteris, which have not polocytic type and copolocytic type. In Pseudocystopteris and Athyrium, the stomatal density is usually above 20 pieces /mm2, but in Cystopteris that is less than 20 pieces /mm2, ranging from 15 to 20.3 Research of tracheary elementsTracheary elements of rhizomes in Pseudocystopteris, Athyrium and Cystopteris were examined by scanning electron microscopy (SEM). The results indicated that the end walls and lateral walls both have perforation plates, whose pit membrane is left more or less. The perforation plates of the three genus could be divided into four types: 1) scalariform perforation plates, without dimorphic width perforation;2) scalarifonn perforation plates with dimorphic width perforation;3) reticulate perforation plates;4) scalariform-reticulate perforation plates. The remnants degree of pit membrane could also be divided into the following three types: 1) partly intact pit membrane on part region;2) threadlike or weblike in structure;3) few or without pit membrane remnants.Judging from the evolution of the perforation plates types, scalariform perforation plates is original, reticulate perforation plates is evolutional, and scalariform-reticulate perforation plates is a intermediate type. Pseudocystopteris has scalariform perforation plates and scalariform-reticulate perforation plates;Athyriumhas scalariform perforation plates and reticulate perforation plates;Cystopteris only has scalariform perforation plates. It shows that Pseudocystopteris and Athyrium have close relationship and the systematic position is relatively higher, and Cystopteris occupies a lower position.At the same time, the observation results show that compared with tracheary elements of angiosperm, the three genuses have unobvious end walls and there are perforation plates or multi-perforation plates on lateral walls. So, we think that the identification of vessle elements and tracheids should depend on the fact that perforation plates exist on the end walls or lateral walls, rather than presence of pit membrane. So tracheary elements which have perforation plates only on the end walls are vessel elements, tracheary elements that have perforation plates or not and whose end walls unobvious are tracheids. Based on the present results, we consider that tracheary elements which conduct water and mineral in ferns and gymnospenn are largely tracheids.4 Morphology and anatomy researchBy comparison with rhizoma, insertion manners of lamina, ornamentation of perispore, indusium and other aspects, we found that Pseudocystopteris is similar to Athyrium on some morphological characters , and basic number of chromosome are both 40 which show that they have close relationship. And that , the similarity of Cystopteris and Athyrium is much less than the former, and basic number of chromosome in Cystopteris is 42.According to inspection on scale of rhizoma, the three genuses have similarity on the shape of scale and lumina, all are lanceolate and long shuttled, but the margin of scales of Cystopteris has hair and glandular hair, while Pseudocystopteris and Athyrium not have this character.Crosscuting the basal of petiole, it was observed that the cross section of three genuses all have meristele, which are amphicribral vascular bundle. The cross section of Pseudocystopteris and Athyrium is oblateness, and the two meristele are sliver shape, distributing in the shape of "A", the xylem in the two meristele are typicalhippocampus type. The two meristeles of Cystopteris on the cross section are nearly round in which the xylem is not typical hippocampus type.Based on the above-mentioned and combined with molecular, cytological and auxanological characters, we conclude that Pseudocystopteris has close relationship to Athyrium, it should be moved to Athyrium. The correct names of seven genus in Pseudocystopteris should be:Athyrium atkinsonii Bedd.Athyrium spinulosum Milde.Athyrium subtriangulare Hook.Athyrium schizochlamys (Ching) M L Wang et H Xu. comb. nov.Athyrium atuntzeensum (Ching) M L Wang et H Xu. comb. nov.Athyrium davidii Christ.Athyrium repens (Ching) M L Wang et H Xu. comb. nov.