Abstract <p>Amaranthin-like proteins are lectins with distinct domain organization, but their functions in plants remain unclear. Flax (<i>Linum usitatissimum</i>) has one of the largest Amaranthin protein family among plant species, with 19 members grouped into three types of domain combinations: single amaranthin domain (A), two amaranthin domains with one aerolysin domain (AAT), and one or two amaranthin domains with one Bet v 1 domain (AB/AAB). In this study, we examined the expression of 13 amaranthin-like genes. Genes encoding proteins with a single amaranthin domain were active during early development and showed temporary upregulation in phloem fibers and xylem tissues after gravistimulation, suggesting possible roles in cell wall rearrangement and biosynthesis. <i>AB2</i> and <i>AAB2</i> genes were mainly expressed in phloem fibers at later stages, indicating possible involvement in phloem fiber formation. <i>AAT1</i> was the only gene clearly expressed during intrusive phloem fiber growth. These results reveal that the different protein domain combinations correspond to distinct, tissue- and stage-specific gene expression patterns, pointing to specialized roles in phloem fiber formation, xylem development, and cell wall dynamics, and highlight candidate genes for further functional studies.</p>