Which phenomenon of fusion involved in the triple fusion in angiosperms?

The phenomenon of fusion involved in the triple fusion in angiosperms is called triple fusion endosymbiosis. Endosymbiosis is a process by which one organism is taken into another for mutual benefit. In the case of triple fusion endosymbiosis, three different organisms are taken into one larger organism. In this process, the three single-celled organisms, namely the cyanobacterium, green alga and apicomplexan, are incorporated into a single, larger organism. This fusion process enables the organism to obtain the nutrients and energy from both the photosynthetic and the autotrophic organisms. This process also helps in the formation of plant tissues, allowing the plant to grow, flower and reproduce.