Probably involved in the RNA silencing pathway. May bind to short RNAs such as microRNAs (miRNAs) or short interfering RNAs (siRNAs), and represses the translation of mRNAs which are complementary to them (By similarity). Plays a role in the maintenance of the indeterminate state of the stem cells in the shoot apical meristem (SAM). Regulates leaf formation through vascular development and may be involved in determining the central domain of the leaf founder region. Expressed in the center of the leaf primordia at plastochron 1 (P1) stage. In the P2 leaf primordia, expressed in the mid-vein and the future large veins. In P3 and P4, expressed in the vascular regions and the future bundle sheath extension cells. Expression in leaf primordia quickly disappears after P4 stage. In the inflorescence meristem, expressed at the predicted site of the next bract, and then in the vascular tissue of the developing rachis-branch. In developing floral organs, expressed in the adaxial side of the palea, lemma and stamen. Malformed leaves with an altered vascular arrangement and abnormal internal structure. Aberrant SAM with reduced OSH1 gene expression. Belongs to the argonaute family. Ago subfamily.