Studies On Phylogeny Of Triblemma (Athyriaceae)

Triblemma Ching is a new genus suggested by Ching Ren-Chang in 1978, and it is a genus with 2 species, Triblemma lancea (Thunb.) Ching and Triblemma zeylanica (Hook.) Ching. The systematic position of Eupteleaceae has been disputed for a long time. The genus has always been included in Diplazium, Zhu Wei-Ming did not adimit the genus when compiling Flora Reipublicae Popularis Sinicae. Sano moved the genus to Deparia according to studies of molecular systematics. Many features of Triblemma Ching were described in the paper, including tracheary elements, epidermis, spore, scale and rachis, so that the sytematic position of Triblemma can be determined.1 Leaf epidermisIn Triblemma and Athyriopsis, the pattern of anticlinal walls of up epidermis is mostly irregular concaveconvex, the shape of the cell is asterism. But Diplazium is characterized by straight anticlinal walls and rectangle or roundish cell. As for the stomatal style, polocytic type, axillocytic type are main pattern, copolocytic type and coaxillocytic type are lesser, anomocytic type is rare in Triblemma and Athyriopsis. The quantity of polocytic type, axilloctic type, copolocytic type and coaxillocytic type are same leave each other in Diplazium. In Triblemma and Athyriopsis, the stomatal density shows a little variation(15~20/inm~2), but that of Diplazium shows much, ranges from 9~ 13/mm~2 (D. pinfaense) to 16~27/mm2 (D. crassiusculum)2 Tracheary elementsTracheary elements of rhizomes in Deparioideae (Triblemma, Dryoathyrium, Lunathyrium, Athyriopsis, Dictyodroma) and Diplazium were examined by scanning electron microscopy (SEM). The results indicated that end walls have the same morphological characteristic and structure as the lateral walls. There are perforationplates (multi-perforation plates) on lateral walls characteristically. According to the characteristics of perforation plates, tracheary elements of Deparioideae could be divided into five types.- scalariform perforation plates, without dimorphic width perforation;scalariform, perforation pit dimorphism;reticulate plates;reticulate-scalariform plates;coarse pored perforation plates. According to the degree of pit membrane remnants, tracheary elements could be divided into the following three types: intact pit membrane on part region;threadlike or weblike in structure;little or without pit membrane remnants.Tracheary elements in ferns and vessel elements in angiosperm have different morphology and transfer mechanism. The new view is raised that the identification of vessle elements and tracheids should depend on the fact that perforation plates exist on the end walls or the lateral walls, rather than presence of pit membrane. So tracheary elements which have perforation plates only on the end walls are vessel elements .Tracheids are tracheary elements whose end walls and lateral walls have the same morphological characteristic or structure,and they have perforation plates or notBased on the present results, we considered that tracheary elements which conduct water and mineral in ferns and gymnosperm are tracheids.Scalariform and perforation pit dimorphism are common characters of Triblemma and Athyriopsis. Triblemma has coarse pored perforation plates, and Athyriopsis has reticulate plates, which suggests that they are relative. But Diplazium has no these characters. So it proves that Triblemma and Athyriopsis have closer relationship. Perforation pit dimorphism and coarse pored perforation plates appear in Triblemma, which may be of some significance in evolution.According to the features of tracheary elements, Athyriopsis and Lunathyrium should be most evolutive, Dryoathyrium might occupy basal position relatively, and the systematic position of Dictyodroma should be between Athyriopsis, Lunathyrium and Dryoathyrium. 3 SporeThe surface ornamentation of perine of Triblemma and Athyriopsis have baculate, lophate processes .But perisporium hyal, or with some folds on that of Diplazium.4 ScalesScales of Triblemma, Athyriopsis and Diplazium are lanceolate, with large lumia and fusiform. The base cells of Triblemma and Athyriopsis are small lumia densely, with no tooth at the margin. There are apparent teeth at the margin of the scale of Diplazium, top end of which is divided into two parts.5 Rachis cross cutTriblemma and Athyriopsis have deep groove on the rachis and costa, conspicuous contract on the both sides of rachis. These two characters are not obvious in Diplazium.Considering the above-mentioned characters, combining studies of molecular systematic, we concluded that Triblemma is relative to Athyriopsis, which conflicts with the tratditional point. So we suggested that Triblemma should be moved to Athyriopsis. The new combinations are Athyriopsis lancea (Thunb.) M. L. Wang et L. Zheng, comb, nov., Athyriopsis zeylanica (Hook.) M. L. Wang et L. Zheng, comb, nov.o...