Spore Morphology of Cyatheaceae in China

Abstract

Scanning electron microscopy and light microscopy were used in a palynological study of eight species of Cyatheaceae in China: Sphaeropteris brunoniana, Alsophila spinulosa, A. latebrosa, A. costularis, A. denticulata, A. gigantea, A. austroyunnanensis and A. khasyana. The first three species of Alsophila are in subgenus Alsophila and the last four are in subgenus Gymnosphaera. The spores of nearly all species of Alsophila examined are characterized by a ridged or modified ridged perine and a granular or verrucate exine, except the spores of A. denticulata and A. austroyunnanensis, which have a smooth exine. Species with a granular or verrucate exine may be advanced in comparison with the species with a smooth exine, implying that the species of Cyatheaceae in China are advanced. The spores of Sphaeropteris brunoniana feature an incipient granular outermost layer and a verrucate exine. Species of Alsophila subgenus Gymnosphaera resemble species of subgenus Alsophila in having a granular or verrucate exine and a ridged perine, supporting the placement of Gymnosphaera within Alsophila rather than recognizing it as a separate genus. Because spores in the species of subgenus Gymnosphaera are more diverse and have a more complicated perine, it is possible that this group is advanced when compared with other species of Alsophila.