Compound leaves, which are composed of multiple independent units called leaflets, show a wide diversity of patterning, ranging from trifoliolate, palmate, pinnate to higher ordered forms. There is agreement that the proximodistal expression patterns of morphogenetic regulators are associated with the compound leaf patterning. However, the mechanisms by which such patterns are established, maintained, and regulated, as well as their functional relationships to the sequential progression of leaflet formation are largely unknown.
