Transcriptional factor that specifically binds 5'-GATA-3' or 5'-GAT-3' motifs within gene promoters (including its own promoter and GATA21 promoter), thus regulating the expression of genes mostly involved in hormone responses and floral organ specification (including genes regulating hormones responses) (PubMed:23335616, PubMed:26390296). Regulates both flower and shoot apical meristem (SAM) development, especially for establishing organ boundaries in shoots and flowers, probably by controlling the number and position of WUS-expressing cells (PubMed:15367721, PubMed:23335616). Coregulates, with AGO10/PNH, the shoot apical meristem (SAM) organization. Regulates floral organ development via the promotion of JAG and NPR5/BOP2 expression. Modulates cytokinin homeostasis in organ boundaries by regulating CKX3 expression (PubMed:26390296). Involved in cell proliferation and differentiation (PubMed:15367721). Required to position the inductive proembryo boundary via the regulation of gene expression and for early embryonic development (PubMed:20643354). Together with GIF1/AN3, mediates cotyledon identity by preventing ectopic root formation through the repression of PLT1 expression (PubMed:22669825). Homodimer (PubMed:23335616, PubMed:26390296). Forms heterodimers with GATA19, GATA22 and GATA21 (PubMed:23335616). Interacts with JAG. Binds to AGO10/PNH (PubMed:26390296). Expressed in vegetative and inflorescence shoot apical meristems (SAMs), axillary (SAMs), floral meristems, developing ovules and stamens, vascular tissues, and in the embryo. In the developing axillary shoot apical meristem (SAM), expressed at the boundary between nascent axillary meristems and the adaxial side of leaves. In all mature SAMs, located at the boundaries between the central SAM and the initiating organ primordia, as well as between the neighboring initiating organ primordia. In the floral meristem, strongly expressed at the boundaries between the meristematic dome and the initiating floral organ primordia, and also at the boundaries between the primordia of different whorls. Expression at the boundaries attenuates as the organ primordia grow apart. In flowers, localized at the boundary between the central meristematic cells and differentiating stamen primordia to later accumulates at the medial ridge region of the carpel. Highly expressed in the developing anthers, in both the tapetum cell layer and microsporocytes. In developing ovules, confined to inner and outer integuments. In aerial tissues, strongly present in phloem tissues (PubMed:15367721). First observed in the whole embryo, but later confined to the center cells of the embryo and provascular tissues (PubMed:15367721, PubMed:20643354). Repressed via a negative regulatory feedback loop. Abnormal flower and shoot apical meristem (SAM) development with fused sepals and reduced organ numbers in all four whorls as well as flatter and smaller meristems (PubMed:15367721, PubMed:23335616). Reduced levels of gibberellins (GA) but increased content of trans-zeatin riboside (ZR) and auxin (IAA) (PubMed:26390296). Coordinated apical shift of gene expression patterns in the basal proembryo, including auxin transporter genes and resulting in apical redistribution of auxin (PubMed:20643354). Altered WUS expression from early embryogenesis (e.g. globular stage) (PubMed:15367721). The double mutant an3 han-30 exhibits severe defects in cotyledon development such as ectopic roots formation at the apical region of the embryo and associated with an abnormal expansion of PLT1 expression from the basal embryonic region to the apical region (PubMed:22669825). The double mutant pnh-2 han-2 has smaller inflorescence meristems (IM) and taller floral meristems (FM) leading to fewer petals. The double mutant han-2 jag-3 exhibits reduced petal numbers, more serrated sepals and narrower petals (PubMed:26390296). 'Hanaba taranu' means 'fewer floral leaves' in Japanese. Belongs to the type IV zinc-finger family. Class B subfamily. Truncated N-terminus. Truncated N-terminus.