“…We used treePL to date the plastome phylogeny and each individual gene tree, and for each we ran cross‐validation tests prior to the final analysis to determine the optimal smoothing parameters (see configuration files for more details, available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.h70rxwdfq [Stull et al., ]). Given the difficulty of consistently calibrating individual gene trees with differences in both relationships and included species, we employed only two calibrations: (1) one for crown eudicots, with the minimum age set at 125.0 Ma (corresponding to the first appearance of tricolpate pollen; Doyle et al., ; Hughes and McDougall, ) and the maximum age set at 135.0 Ma (corresponding approximately to the oldest reliable fossil evidence of angiosperms; Trevisan, ; Brenner, ; Friis et al., ; Coiro et al., ); and (2) another for crown Asteridae , with the minimum age set at 115.75 Ma (based on the penalized likelihood minimum estimate from 100 ML bootstrap trees in Magallón et al., ) and the maximum age set at 125.0 Ma (the first fossil appearance of eudicots, the broader clade including Asteridae ). This more minimal calibration scheme allowed us to consistently calibrate nearly all gene trees, while weighting the significance of the eudicot calibration, which is generally considered one of the better angiosperm calibration points in that it likely captures eudicots relatively close to their actual geologic origin (Friis et al., ).…”