Probable transcription activator that binds to the DNA sequence 5'-CAAT[AT]ATTG-3'. May be involved in the regulation of gibberellin signaling. Homodimer (Probable). May form a heterodimer with HOX5. Expressed in leaf and floral organ primordia, floral meristems, embryonic axis and cells surrounding the vascular bundles. Expressed in the vasculature of roots, stem, leaves and spikelets, and in the vascular bundle of the scutellum in embryos. By gibberellin. Down-regulated in leaves by drought stress. Belongs to the HD-ZIP homeobox family. Class I subfamily.