About the cover: TOO MANY MOUTH (TMM) plays an important role in ligand-receptor signaling modules to regulate the number and pattern of stomata in epidermis. In this issue, Yang et al. (pp. 539–549) report that ARGONAUTE1 (AGO1) acts downstream of TMM and negatively regulates SPEECHLESS expression to control the division of stomatal lineage ground cells. The picture shows the expression pattern of stomatal lineage marker pTMM::TMM-GFP in ago1 mutant.