You treat Arabidopsis seed with ethyl methanesulphonate (EMS). In a particular seed embryo, this chemical causes a loss of function mutation in a gene involved in trichome formation. The plant that develops from this embryo has a phenotype similar to the wild type (with trichomes). In contrast, after the selffertilization of this plant, a few of its progeny is glabrous (without trichomes). What accounts for these observations?.