Reconstruction of light environment for pennsylvanian marattialean ferns: Insights from ftir analysis of living cyathea caracasana

Abstract

Fourier transform infrared spectroscopy (FTIR), a nondestructive test, has been successfully applied as an investigative technique to Carboniferous-age seed ferns, and some true ferns, but not to living ferns. In this study, we applied the technique to the tree fern Cyathea caracasana that grows in bright sunlight in the Andean mountains to primarily test applicability to a living fern. The secondary purpose concerns accumulating phytochemical parameters for a comparative study of Carboniferous palaeocological counterparts. The study sample comprises two oven-dried ultimate pinnae that are subdivided into five sample sets, designed to represent sterile pinnate tips, fertile basal pinnule portions, empty sporangia enveloped in indusia removed from the latter, and the ultimate pinna rachis. Two additional sample sets were used for spectral quality control. We document that FTIR furnished quality spectra suitable for the interpretation of phytochemical calculations from these sample sets. Moreover, based on the absorbance spectra, we were able to reduce the five sample sets to three related-chemical groups. The reduction is principally based on aliphatic (carbon-atom joined open chain structures) and oxygen-containing moieties, but factoring into the related chemical groups the cellulose, mirroring, although not perfectly, predominating organ tissue in the subdivision of the sample sets. In effect, we have isolated the main chemical parameters for the foliage and sporangia (excluding spores) of C. caracasana.