CONSERVED MERISTEM GENES. “Leaves in vascular plants are produced by determinate growth on the flanks of indeterminate shoot apical meristems. Inderminate growth of the shoot apical meristem is controlled by the knotted-like homeobox gene family (KNOX). KNOX genes are present in some green algae (e.g. Acetabularia), mosses, ferns, gymnosperms and angiosperms and their function may be highly conserved.”
http://aob.oxfordjournals.org/content/96/3/345.full.pdf