This dataset contains records of the optically measured mean leaf traits (adaxial flavonol & anthocyanin index and chlorophyll index, units are an optical index of leaf/epidermal relative absorbance) from a large set of plant taxa growing at alpine botanical garden at the Joseph Fourier Field Station (Université Grenoble Alps, France; 2100 m a.s.l.; 45°2' 9" N, 6°23' 59" E) and at Kumpula Botanical Garden (LUOMUS, University of Helsinki, Finland; 14 m a.s.l.; 60° 12' 7" N, 24° 57' 26" E;). Optical measurements were made during the summers of 2014 and 2015 with a leaf-clip Dualex Scientific + (Force-A, Paris-Orsay, France) and all detailed information about the methods are published in Hartikainen and Robson, doi: 10.3389/fpls.2022.1058162. This dataset also includes spectrophotometer measurements of absorbance by phenolic compounds in leaf extracts in acidified methanol (abs range 290-400 nm) and mini-PAM measurements of chlorophyll fluorescence from different subsets of taxa at alpine botanical garden. All details concerning these data are given in Hartikainen and Robson (doi: 10.3389/fpls.2022.1058162) and its Supplementary Materials. Sheet with explanation of the different variables is also included.

A grant from eLTER-Europe Transnational Access partially funded this research at the Station Alpine Joseph Fourier, Lautaret Garden-UMS 3370 (Univ. Grenoble Alpes, CNRS, SAJF, 38000 Grenoble, France); a member of AnaEE-France. T.M. Robson and S.M. Hartikainen were partially supported by Academy of Finland decisions # 266523, #304519 and #324555.