All of the post-embryonic, above-ground structures of seed plants are generated from the shoot apical meristem (SAM), which acts as a reservoir of stem cells. Members of the flax genus (Linum spp.) have been used historically as models for the study of SAMs (Esau, 1942). Cultivated flax (Linum usitatissimum) is grown in more than 50 countries for its seeds or its stem phloem (bast) fibers (Rubi...