Embryos from nondormant seeds grow more rapidly than embryos from dormant seeds when imbibed on media containing mannitol or PEG as osmotica. A, Micrographs of embryos 7 d after removal from nondormant or dormant C24 Arabidopsis seeds. B, Surface area of isolated embryos growing on a substrate containing up to 500 mOsmol mannitol or PEG for 2 d relative to the surface area on day 0. C, Relative surface area of cotyledons, hypocotyls, and roots 1 or 2 d after placing freshly isolated embryos from dormant (D) or nondormant (ND) C24 Arabidopsis seeds on 300 mOsmol mannitol or 300 mOsmol PEG.