Study On The Spore Morphology Of Polypodiales(Filicales)from China

Polypodiales (Filicales) is the largest order in Pteridophyta, occupying about 90% of the total fern species. According to Ching抯 system (1978) it comprises 47 families, 197 genera, and more than 1,800 species in China. In the present paper, the spores of 690 species (collected in China) of Polypodiales, belonging to 47 families 154 genera, were examined under scanning electron microscope (SEM). The morphologic features of the spore of each species were described. Based on structure of exospore and perispore and surface ornamentation, the spores of this order are divided into thirty-three types, and the structure of spore wall of main types were researched by TEM. The relationships of the spore morphology and the system of this order were discussed. At the point of view of spore morphology, the rationality of Ching抯 system were analyzed. The development of perispore of Dryoathyriwn corecmwn (Christ) Tagawa was studied under LM, SEM and TEM in this paper. All these provided information for palynology and systematics of Pteridophyta. The types of spore morphology of the order Polypodiales can be divided into several groups as follow. Group Lygodoid type: Trilete, rare monolete, exospore plain, elevated or depressed, perispore plain or tuberculate. This group includes Diplopterygoid type, Plagiogyroid type, Lygodoid type, Scandens-Lygodoid type, Cryptogrammoid type and Ceratopteroid type. They are the members of Plagiogyriaceae, Gleicheniaceae, Lygodiaceae, Parkeriaceae, Sinopteridaceae (Cryptogramma) and Schizaeaceae. Group Dennstaedtoid type: Trilete, exospore plain, perispore from thin to thick, psilate or scabrate. This group includes Adiantoid type, Dennstaedtoid type, Alsophiloid type, Sphaeropteroid type and Hypolepoid type. Dennstaedtiaceae, Monachosoraceae Cyatheaceae, Adiantaceae, Hemionitidaceae (Coniogratnme) Acrostichaceae, Antrophyaceae, Vittariaceae (part) and Hypolepidaceae belong to this group. Group Aleuritopteroid type: Trilete, exospore plain, perispore thick, pultaceous. This group includes Aleuritopteroid type and Pteridoid type. They are the members of Sinopteridaceae (part), Hemionitidaceae (part) and Pteridiaceae. Group Pteroid type: Trilete, with cingulum and margo, exospore thick and the surface ornamentation is formed by the exospore, perispore thin, compact. This group includes Pteroid type, Cibotoid type and Cheiropleuroid type. Pteridaceae, Taenitidaceae, Hemionitidaceae (part), Sinopteridaceae (Onychiwn), Dicksoniaceae and Cheiropleuriaceae belong to this group. Group Hymenophylloid type: Trilete, green, wall thin, surface papillate. This group only includes Hymenophylloid type, There is only one family Hymenophyllaceae in this group. GroupGrammitoid type: Trilete, subglobose, exospore thick and the surface ornamentation is formed by the exospore, perispore thin. This group includes Grammitoid type and Loxogrammoid type. Grammitidaceae and Loxogrammaceae in Hymenophyllaceae belong to this group. Group Vittaroid type: Monolete, long reniform, exospore and perispore plain. This group only includes Vittaroid type. There are Vittariaceae, Pleurosoriopsidaceae, Platyceriaceae and Lindsaeaceae (Stenoloma) in this group. Group Polypodoid type: Monolete, reniform, exospore and perispore plain or concavo- convex, verrucate, tuberculate, undulate, granulate etc. This group onLy includes Polypodoid type. Polypodiaceae, Gymnogranirnitidaceae, Drynariaceae, Davalliaceae, Nephrolepidaceae, Dipteridaceae, and Pteridaceae (Histiopieris) belong to this group.