Probable transcription factor required to initiate organ founder cells in a lateral domain of shoot meristems. Involved in leaf formation. Predominantly expressed in tissues enriched for shoot meristems and young lateral organ primordia. First expressed in lateral domains of shoot meristems. It is then expressed in the margins of young lateral organ primordia. Not expressed in roots, seedling leaves or fully expanded coleoptiles. Also expressed in vegetative shoot apices (five leaf primordia and the SAM) and in the male inflorescence. Expressed at high level in the female inflorescence. Belongs to the WUS homeobox family.