Tetraploid tobacco plants (Nicotiana tabacum) derived from cultured cell lines (TC) are partially cross‐incompatible with their diploid progenitors (C). C × TC crosses (TC‐derived tetraploids as the pollen parent) yield only 2% viable seed. The remaining seeds are normal size but lack an embryo (apoembryonic seeds). Apoembryonic seeds do not occur in the reciprocal TC × C crosses. Sections of ovules from C × TC crosses revealed that an embryo formed but that embryo growth slowed at 5 days postpollination and that by the 12th day following pollination, the embryo had disappeared although the ovule continued to develop. Endosperm degeneration occurred concurrently with embryo death. Culturing ovules from C × TC crosses has increased the yield of F1plants from 2% to as much as 25% indicating that embryo rescue is possible. Surviving F1plants from TC × C crosses have close to triploid chromosome numbers and are fertile.