Lignins are phenolic polymers that are differently incorporated between and within the cell wall layers of specific plant cell types. Lignins are essential for plant biomechanical support, water conduction, intercellular cohesion and cell wall hygroscopy in vascular plants (Blaschek et al., 2024). To fulfil these various roles, each cell wall layer and cell type differently and specifically control lignin spatial distribution, concentration and chemistry (Pesquet et al., 2025). At the molecular level, lignins are built by releasing monomers in cell walls, which are then oxidized by phenoloxidases and combinatorially assembled into a polymer. However, several aspects of lignins remain largely unknown to date. At the subcellular level, what are the mechanisms enabling the spatial restriction of specific lignin chemistries to distinct cell wall layer nm apart? At the cellular level, how does lignin chemistry impacts plant cell wall hygroscopy and biomechanics? At the plant level, how do cell specific lignin structures support distinct physiological properties such as water conduction? We addressed these unknowns by analyzing series of genetically engineered plants with quantitative variations in lignins using various chemical and mechanical imaging methods with cellular to subcellular resolution (Ménard et al., 2022; Blaschek et al., 2023). We showed that: (i) at the subcellular level, combinations of different phenoloxidases control the cell layer lignin specificity for each cell type, (ii) at the cell level, whole cell wall biomechanics and hygroscopy rely on specific lignins that differ between cell types and morphotypes, and (iii) at the whole plant level, stem lodging and plant water conduction depend on differences in cell specific lignins. Our results illustrate the importance of lignin chemical diversity at the cellular and subcellular levels for whole plant growth under developmental and environmental constraints, such as the ones caused by climate change.