Which of the following processes occurs only in angiosperms?
Formation of secondary nucleus by fusion of two polar nuclei.
Formation of secondary nuclues by fusion of two polar nuclei is a characteristic feature of angiosperms. Double fertilization is a characteristic of angiosperms. One fertilization involves fusion of sperm and egg to produce a diploid zygote. Two polar nuclei then fuse to become a secondary nucleus. Second fertilization involves fusion of sperm with secondary nucleus to produce a triploid endosperm.