About the cover: The compound leaf of Lotus japonicus possesses 5 visible leaflets and 2 degenerated leaflets. In this issue, Wang et al. (pp. 419–433) show that multiple genetic components and plant hormones are integrated to determine leaf complexity. PFM/LjLFY and PFO/LjUFO determine the basipetal leaflet initiation and the leaflet number. Down-regulation of PFM/LjLFY and PFO/LjUFO genes results in reduced leaf complexity.