This is a 15-year dataset of photosynthetic CO2 response curves, measured in the field, for 51 different plant species (mostly trees) over 20 different sites in N. America, Australia, and Europe including free-air CO2 enrichment (FACE) sites and particularly EucFACE. Ecosystem types range from arid shrubland, temperate deciduous forest to open eucalypt woodland and wet sclerophyll forest. Species names are done according to the Taxonomic Name Resolution Service TRNS. The raw measurements as output from the Li-Cor 6400 portable photosynthesis system and the computed carboxylation capacity and electron transport capacity for all measurements are provided. The data contribute to the De Kauwe et al paper "A test of the 'one-point method' for estimating maximum carboxylation capacity from field-measured, light-saturated photosynthesis" in New Phytologist (doi: 10.1111/nph.13815). K. Crous is the data co-owner.