Receptor kinase that regulates inflorescence architecture and organ shape as well as stomatal patterning, including density and clustering, together with ERL1 and ER. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Mostly expressed in developing organs, including bud clusters, flowers, siliques and young rosettes. Also detected in mature aboveground organs, such as leaves, stems and pedicels, but barely in roots. At the vegetative stage, strongly expressed in the shoot meristem, leaf primordia and juvenile leaves. At the reproductive stage, localized in the young developing flowers. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.