Abstract: Spore morphology of 8 species 2 varieties of genus Onychium from China was examined by SEM. Each spore was described detailed. The taxonomic status of Onychium was discussed. The spore morphology of the genus is uniform, trilete, radiosymmetric, polar view obtuse triangular or tri-rounded, equatorial view elliptical, super semiorbicular or fan-shaped. Perispore thin, exospore swells to form contour of spore ornamentation. The spore has a few unique structures such as equatorial flange, proximal ridge and distal ridge. Difference between species mainly appears as different distal surface ornamentation. At the point of spore morphology, Onychium is far distinguished from other genera in Sinopteridaceae. However, it is similar to genus Pteris of family Pteridaceae. We suggest separate Onychium from Sinopteridaceae to Pteridaceae.

Key words: Onychium, Spore morphology, China