Probable transcription factor that acts as negative regulator of trichome branching in association with HDG11 (PubMed:16778018). Seems to promote cell differentiation (PubMed:25564655). May regulate cell differentiation and proliferation during root and shoot meristem development (PubMed:25564655). Acts as positive regulator of SCL18/LAS expression (PubMed:25358340). Involved, together with PDF2, in the regulation of flower organs development by promoting the expression of APETALA 3 (AP3) in the epidermis and internal cell layers of developing flowers (PubMed:23590515). Interacts with BBM. Expressed in apical meristems and young epidermal tissue including trichomes and stipules. Expressed in lateral root tips, the L1 layer of apical inflorescence meristems and early flower primordia, carpel and stamen filament epidermis, stigma papillae, ovule primordia, nucellus and embryo. During embryo development, expressed in all cells at the 4- and 16-cell embryo stages (PubMed:25564655). Expression is restricted to the protoderm from the globular stage onward (PubMed:25564655). In primary and lateral roots, observed in the epidermis, the outer layer of columella cells and lateral root cap (PubMed:25564655). No visible phenotype under normal growth conditions, but the double mutants hdg11 and hdg12 exhibit excess branching of trichomes (PubMed:16778018). The double mutant pdf2-1 hdg12-2 exhibits abnormal flowers with sepaloid petals and carpelloid stamens in association with a reduced expression of APETALA 3 (AP3) in the epidermis and internal cell layers of developing flowers (PubMed:23590515). Belongs to the HD-ZIP homeobox family. Class IV subfamily. Intron retention. Intron retention.