A Systematic Study On The Fern Genus Pyrrosia Mirbel

About70species of the genus Pyrrosia Mirbel (Polypodiaceae, Pyrrosioideae) are mainly distributed in the mainland of Asia, epiphytic or epilithic, sometimes terrestrial. The genus Pyrrosia Mirbel is one of the key groups in Polypodiaceae, and it is different from other genera of Polypodiaceae in special venation pattern and indumenta.Based on the collection of literatures and checked in the specimens in herbaria, the scale, lamina indumenta, venation pattern, spore ornamentation and mineral element of the genus Pyrrosia were investigated in the present study. A new infrageneric system was supported, and all Chinese species were treated at27species,3variety and2forms in this genus. The major results of the dissertation were summarized as follows:1Rhizome scaleThe characters of scale of38species of the genus Pyrrosia were observed under the anatomical lens. It was showed there were3attachment, such as peltate, pseudopeltate and basifix;4shape types, such as lanceolate-acuminate, lanceolate-caudate, ovate-subulate and ovate;3colors, such as light brown, dark brown, brown-black and some intergradations (concerned growing age);4marginal types, including entire, dentate, ciliolate, and hair at apex.2Venation patternThe characters of venation pattern of10species of Pyrrosia and6species in other5genera were studied in Polypodiaceae. It was showed that free and anatomizing venation pattern were existed in Polypodiaceae. There were2venation patterns of Pyrrosia, Campyloneuroid type and Drynarioid type, included in anatomizing venation pattern. It was implied there be a evolutionary relationship between Pyrrosia and Campyloneurum.3Lamina indumentThe characters of lamina indument of38species of Pyrrosia were examined under anatomical lens and scanning electron microscopy (SEM). It was showed the hairs of the fronds were almost exclusively stellate with being composed of different rays. There were3shapes of rays, including lanceolate (light brown), aciculate (dark brown) and wooly (white);2types of rays, such as monomorphic and dimorphic. So,5types of indument were discovered in the Pyrrosia. These characters could be used to distinguish some species.4Spore ornamentationThe spores of19taxa of the genus Pyrrosia were examined by means of light microscopy (LM) and SEM. It was showed the shapes of the spores were all kidney-shaped, bilaterally symmetric, monolcte, while the color of the spores was yellow. There were two main ornamentation types, such as verrucate and tuberculate. The spore morphological features were polymorphism, including Pyrrosia rupestris-type, Pyrrosia subfurfuracea-types and Pyrrosia christii-type. The evidence from spore ornamentations was stable, and could be used to differentiate the affined species in this genus.5Mineral elementIn this dissertation, the contents of9mineral elements in9species of Pyrrosia were determined by atomic absorption spectrophotometry (AAS). It was provided for baseline data on mineral element levels in fern genus Pyrrosia. The element contents change in wide range. It implied that the species should have an inherent characteristic absorption and accumulation for the determined mineral elements, and might control quality of herbal medicines, to provide chemotaxonomy information.6Infrageneric systemBased on the characters of spore ornamentations, the shape of blade, venation pattern, scale, lamina indumenta, etc.. two subgenera and six sections of the genus were presented:subgen. Pyrrosia, subgen. Porosae S. G. Lu et L. H. Yang; sect. Nummulariifoliae S. G. Lu et L. H. Yang. sect. Pyrrosia. sect. Lanceolalae S. G. Lu et L. H. Yang, sect. Drakeanae (Ching et Shing) S. G. Lu et L. II. Yang. sect. Porosae, sect. Costalae (Ching et Shing) S. G. Lu et l..H. Yang. A key to the Pyrrosia species was given. 7Taxonomic revisionBased on the collection of literatures, checked in the specimens and type specimens in Herbaria all over the world (PE, PYU, KUN, IBSC, HITBC, BM, K), combining field, culture and morphological observation, all species in this genus Pyrrosia from China were made classification. As a result,27species,3variety,2forms were recognized from China in six sections. Nine species were treated as synonyms, such as P. caudifrons and P. fuohaiensis were treated as the synonym of P. heteractis; P. fengiana, P. bonii, and P. similis were treated as the synonym of P. bolhii; P. gralla was treated as the synonym of P. davidii; P. dimorpha was treated as the synonym of P. assimilis; P. adnascens f. calcicola was treated as the synonym of P. adnascens; P. porosa var. mollissima was treated as the synonym of P. porosa.3species was reduced to variety, i. e. P. adnascens and P. mida were reduced to the variety of P lanceolata:P. shennongensis was reduced to the variety of P. boothii.2species were reduced to forms, i. e. P. ensata was reduced to the form of P. lingua; P. pseudodrakeana was reduced to the form of P. drakeana, and1species were temperately treated as doubtful species in the present study.