The evolutionary emergence of land plants 450 million years ago required the acquisition of lignins, absent from their ancestor mosses and algae. Different concentrations and compositions of lignins accumulate within and between the cell wall layers of specialized cell types to confer distinct physiological functions. In roots, lignins establish the impermeable intercellular barrier as localised depositions for the endodermal tissues while also providing mechanical reinforcement for water conduction and skeletal support as a pitted continuum for the xylem tissues. This dual role allows lignins to provide waterproofing and/or mechanical resistant properties. Specific spatial changes in cell wall lignin quantity and chemistry depend on extracellular enzymes called PHENOLOXIDASEs, including H2O2-dependent PEROXIDASEs and O2-dependent LACCASEs, oxidizing released phenolic compounds (Blaschek and Pesquet, 2021). However, to date, only Arabidopsis thaliana has been used to study cell-specific lignification, with endodermal lignification depending on several PEROXIDASE  paralogs (Rojas-Murcia et al., 2020) and xylem lignification depending on several LACCASE paralogs (Zhao et al., 2013; Blaschek et al., 2023). To understand how evolutionary pressures would affect cell type-specific lignins and their associated genes, we compare terrestrial Arabidopsis thaliana with two related grass species: the terrestrial grass Brachypodium dystachyon and the seagrass Zostera marina, which has returned from land back to the sea 135 million years ago. Comparison using spatial chemical imaging, wet chemistry analysis of lignins and phenolic compounds, together with genome organization, revealed that the evolutionary conservation, divergence, and/or loss of lignins in specific cell types is mainly associated with PHENOLOXIDASE genes than phenolic compounds biosynthetic genes. Our investigation reveals that cell type-specific lignification depends on distinct gene gain or loss during plant evolutionary adaption to new environments. The evolutionary shift in lignin to phenolic compound allocation due to gene loss directly adjusted lignin waterproofing and mechanical properties.