Environmental signals have been shown to modulate development by increasing or decreasing the levels of EPF ligands, which modulate SPCH protein level through downstream phosphorylation cascades, or by affecting SPCH expression by DNA methylation at the SPCH locus. SPCH, presumably in combination with its binding partners ICE1/SCRM2 binds to over 8,000 targets. This massive reprogramming potential may be needed to create the stem-cell behavior of meristemoids and make them competent to respond to multiple other signals to modulate leaf size and stomatal density in response to the environment. After an initial pulse of SPCH activity, levels of SPCH (low or high) will shift the balance between differentiation and continued renewal, respectively. Solid lines indicate experimentally verified responses to SPCH, dotted lines indicate predicated responses.