Data from: Biomechanical and leaf-climate relationships: a comparison of ferns and seed plants

Premise of the study: Relationships of leaf size and shape (physiognomy) with climate have been well characterized for woody non-monocotyledonous angiosperms (dicots), allowing the development of models for estimating paleoclimate from fossil leaves. More recently, petiole width of seed plants has been shown to scale closely with leaf mass. By measuring petiole width and leaf area in fossils, leaf mass per area (MA) can be estimated and an approximate leaf life span inferred. However, little is known about these relationships in ferns, a clade with a deep fossil record and with the potential to greatly expand the applicability of these proxies. Methods: We measured the petiole width, MA, and leaf physiognomic characters of 179 fern species from 188 locations across six continents. We applied biomechanical models and assessed the relationship between leaf physiognomy and climate using correlational approaches. Key results: The scaling relationship between area-normalized petiole width and MA differs between fern fronds and pinnae. The scaling relationship is best modeled as an end-loaded cantilevered beam, which is different from the best-fit biomechanical model for seed plants. Fern leaf physiognomy is not influenced by climatic conditions. Conclusions: The cantilever beam model can be applied to fossil ferns. The lack of sensitivity of leaf physiognomy to climate in ferns argues against their use to reconstruct paleoclimate. Differences in climate sensitivity and biomechanical relationships between ferns and seed plants may be driven by differences in their hydraulic conductivity and/or their differing evolutionary histories of vein architecture and leaf morphology.

Usage Notes

Leaf mass, leaf area, petiole width, and leaf physiognomic measurements of globally distributed ferns (Appendices S1a, S1b)Peppe et al_Appendices.xlsxFern images from Baylor University HerbariumZipped folder with images of ferns from Baylor Herbarium. Folder also includes ReadMe file and image key.Baylor ferns.zipFern images from Queensland HerbariumZipped folder with images of ferns from Queensland Herbarium. Folder also includes ReadMe file and image key.Queensland ferns.zipFern images from Te Papa HerbariumZipped folder with images of ferns from Te Papa Herbarium at the Museum of New Zealand Te Papa Tongarewa. Folder also includes ReadMe file and image key.Te Papa ferns (2).zipFern images from US National Herbarium (part 1)Zipped folder with images of ferns from USNH. Folder also includes ReadMe file and image key.USNH ferns_1.zipFern images from US National Herbarium (part 2)Zipped folder with images of ferns from USNH. Folder also includes ReadMe file and image key.USNH ferns_2.zipFern images from Waikato HerbariumZipped folder with images of ferns from Waikato Herbarium. Folder also includes ReadMe file and image key.Waikato ferns.zip