Abstract: This paper is the first report of an investigation on the spore morphology of Chinese ferns. Spore morphology of 20 species (10 species from China and 10 species from other countries) in the genus Lygodium (Lygodiaceae) was investigated under scanning electron microscope (SEM) and transmission electron microscope (TEM). The spores are tetrahedral-globose, trilete, rarely monolete. The surface ornamentation of the spores can be divided into four main types: In type I , the surface of spores is tuberculate or spheroid-tuberculate. Most of the species of the genus have this type of surface ornamentation of spores. In type II , the surface of spores is smooth. L. palmatum, L . subareolatum , L . yunnanense and L . volubile have this type of surface ornamentation of spores. In type III, both the distal and equatorial areas of spores are coarsely verrucate, while the proximal area is smooth. L. dimorphum, L. digitatum and L. kingii have this type of surface ornamentation of spores. In type IV, the surface of spores is coarsely reticulate. L. scandens and L. reticulatum have this type of surface ornamentation of spores. The surface contours of the reticulate type (type IV) are formed by the exospore, while that of the other types (types I, II, III) are formed by the perispore. The surface ornamentation of spores seems to be stable within species and thus is of important value in the taxonomy of the genus Lygodium.

Key words: Pteridophyte, Spore morphology, Lygodiaceae, Lygodium, China