Plants were classified into various branching types depending on the presence of branches in a given quarter (see Figure 1 for more details). a2B indicates secondary branching. The orange (Georgia), black (Iowa), and blue (British Columbia) Xs indicate significant SNPs at the three different locations. When more than one association was detected on a single linkage group (LG), the associations were labeled alphabetically based on their position in the LG. The position of the B locus corresponds to the associations on LG 10a (see methods for details).