A Taxonomic Revision Of The Fern Genus Athyrium Roth S. Str. From China

Based on field investigation and examination of specimens of Athyrium Roth in herbaria, as well as examination of spore morphology and leaf epidermis of more than 20 species of the genus under scanning electronic microscope (SEM), the genus (s. str.) from China was taxonomically revised in this paper. Its geographic distribution and areal-type (including subtypes) were analyzed, and the centers of its distribution, differentiation, and origination were deduced as well. With comparative morphology study of recent and fossil species, the evolutional trend of the morphological characters of Athyrium Roth was supposed.1,The five morphological characters of rhizome type, with or without spine, sorus shape, with or without enations on acroscopic position of pinna base, and with or without squarrose-glandular hairs are stable and can be used for infrageneric classification of Athyrium. The other morphological characters, such as shape of lamina or pinna and with or without petiole of pinna, can be used as species-recognizing characters. But the characters of division of lamina, colour of scales, petioles, rachises, costae and costules, amount of hairs, and lobe shape, are not suitable to be used for species identification separately. The spore surface ornamentation of the genus is polymorpholic, and more or less species-specific, so that it can be used as evidence to affirming whether the species whose independent species status is uncertain or debatable is valid or not. The affinity of species from the genus could be deduced on the basis of leaf epidermal features.2,In this paper the Chinese Athyrium Roth s. str. was classified into 10 sections, 3 series; 13 names were reduced to new synonyms; 7 species were treated as varieties; A. praticola Ching should be a synonym of A. vidalii (Franch. et Sav.) Nakai, A. tenuifolium Y.T.Hsieh et Z.R.Wang a synonym of A. dubium Ching. Thus 82 species, 15 varieties, and 1 form were recognized from China.3,Short spine are present on adaxial costae of A. pachyphyllum Ching.4,A lectotype specimen was assigned to A. suprapubescens Ching.5,The species of Athrium Roth s. str. from China belong to the areal-types of Tropical Asia, East Asia, and Endemic to China. The Hengduan Mountains are regarded as centers of distribution and differentiation, but not origin of the genus. The genus possibly originated in the Early Cretaceous and the origin center of it was possibly boreal in temperate flora.