Modulates cell morphogenesis by regulating cell wall formation and assembly, and/or growth polarization. Together with LRX2, component of the extracellular mechanism regulating root hair morphogenesis and elongation. Mostly expressed in roots, also present in stems at low levels. In roots, confined to differentiation zones, the collet, and meristematic cells of tips. By ethylene. Hydroxylated on proline residues in the S-P-P-P-P repeat. O-glycosylated on hydroxyprolines. No visible effect. Enhances LRX1 disruption phenotype when associated with LRX1 disruption; frequent rupture of root hairs soon after their initiation.