Spore morphology of the north Asian members of Cystopteridaceae

Abstract

Spores of Cystopteridaceae from northern Asia were examined using scanning electron microscopy. To evaluate the utility of spore morphology in the taxonomy of each genus, we examined spores of 14 species: seven species each of Gymnocarpium and Cystopteris. Among these are 12 species occurring in northern Asia and two species from other regions for comparative studies. The study focused particularly on perispore characters and spore size. Spores of all species examined are monolete, bean-shaped, with a range in spore size of 26–56 × 18–37 μm for Cystopteris and 25–48 × 16–34 μm for Gymnocarpium. The perispore is morphologically diverse within Cystopteris, but less so within Gymnocarpium. The perispore of the Cystopteris spores is characterised by folds and spines that are separate or form complex sculptural elements. Sacci, ridges and flanges, sometimes on the same spore, are characteristic of the perispore of Gymnocarpium. Spores have straight laesura over which the perispore forms a crest. The crest represents a high and flat fold, which is entire, foveolate or reticulate.

Keywords:

• ferns
• Gymnocarpium
• Cystopteris
• perispore sculpture
• spore size

Acknowledgements

The authors are grateful to C. N. Page (University of Exeter, Penryn, Cornwall, UK) for the constructive discussions and consultations concerning the content of this paper and help with the English language and for collecting Cystopteris diaphana in Cornwall. Many thanks to C. Rothfels (Duke University, Durham, NC, USA) for the very useful comments and suggestions. The authors also thank the head of the Tomsk Centre of Material Science (Tomsk State University, Tomsk, Russian Federation), V. M. Kuznetsov, for the opportunity to use the SEM. The authors are grateful to the curators of the Herbarium LE (Saint Petersburg, Russian Federation) for the opportunity to obtain spore samples in three Gymnocarpium species. This work was supported by the Program ‘D.I. Mendeleev Scientific Fund’ of the Tomsk State University, Agreement between the Ministry of Education and Science of the Russian Federation and Tomsk State University (BIO-GEO-CLIM) no. 14.B25.31.0001.

Additional information

Funding

This work was supported by the Russian Foundation for Basic Research [13-04-01715].