in angiospermous plants, the formation of an embryo in a seed without fertilization but with stimulation by the contents of the pollen tube that penetrates the embryo sac. The seed’s endosperm, which provides nutrients to the embryo, usually forms only after the spermatozoid fuses with the polar nuclei of the embryo sac. Pseudogamy is characteristic of many species of meadowgrass, cinquefoil, blackberry, and buttercup.