Data from: Three decades of experimental nitrogen fertilization increases the frequency of a defensive plant morph

Data supporting the publication Three decades of experimental nitrogen fertilization increases the frequency of a defensive plant morph (doi: 10.1002/oik.11181). The study compares tall goldenrod (Solidago altissima) plants growing in a long-term nitrogen addition field experiment at the Kellogg Biological Station LTER Main Cropping System Experiment (Treatment 7--Succession). The main phenotype examined is stem nodding, a dimorphic architectural defense against apex galling herbivores. The presence of galls was also recorded, along with plant size metrics at various time points. The data are available and described in detail via the Environmental Data Initiative repository (https://doi.org/10.6073/pasta/b34ad9d15491c07644abe686f358cb4b).We surveyed naturally occurring tall goldenrod (Solidago altissima) plants in a long-term nitrogen addition field experiment at the Kellogg Biological Station's T7 untilled succession plots in the Main Cropping System Experiment (https://lter.kbs.msu.edu/research/long-term-experiments/main-cropping-system-experiment/). We collected data on the defensive stem nodding morph (which helps plants evade apex-galling herbivores) and presence of galls in 2016, 2021, and 2022.