Plant stem cells secrete peptides that, after processing to release the active form, prevent neighboring cells from adopting a stem cell fate by activating a leucine-rich repeat (LRR) receptor-mediated pathway. Other plant meristematic cell fate decisions, such as those made during the patterning of veins and stomata, also appear to be controlled by similar LRR receptor pathways that are activated by secreted peptide signals. It is therefore probable that peptide ligands regulate meristematic activity in many plant developmental processes.