At the POC meeting on 11-8-11, we decided to add a term for embryo stage, is_a sporophyte vegetative stage. Proposed definition is based on our definition of plant embryo (PO:0009009).
proposed def. of embryo stage (PO:0025369): A sporophyte vegetative stage that occurs during the interval between the first cell division and one of the following: germination in seed plants, formation of the first true leaf after the cotyledon(s) in pteridophytes, when the apical cell stops dividing and the sporangium begins to develop in bryophytes, or the beginning of the formation of organs (roots, shoot axes, or leaves) in cultured plant embryos.
Comment: Succeeds the zygote stage. The embryo stage generally starts after the first division of a zygote, but in the case of adventitious embryos, somatic embryos, other embryos that arise through apogamy, and cultured haploid embryos, it begins after the division of a single cell that is not a zygote. The end of the embryo stage varies among taxa.