Probable transcription repressor involved leaf development. Binds to the DNA sequence 5'-CAAT[GC]ATTG-3'. May act as a regulatory switch to specify provascular cell fate. Homodimer (Probable). May form a heterodimer with HOX2, HOX3 or HOX7. Expressed in root provascular and vascular cylinder, provascular and vascular strands of leaves, provascular and vascular strands of the whole panicle, in mature embryo provascular bundles of scutellum and embryonic axis and provascular and vascular strands of young immature spikelet organs. Expressed in differentiating and differentiated xylem and phloem elements, and in outer and inner bundle sheath cells of all vascular bundles. Expressed in auricles, ligules, culm, guard cells brac hairs and pollen. By auxin and sucrose in primary root apical region. By wounding in leaves. Belongs to the HD-ZIP homeobox family. Class II subfamily.