Describe the post-fertilisation changes in a flower
Final answer: Post-fertilisation changes are defined as the series of events after fertilization (actually double fertilization) via which the zygote develops into an embryo, the fertilized ovules into seeds & the fertilised ovary into a fruit. Once the double fertilization (i.e., the fusion of a male gamete with an egg followed by the fusion of another male gamete with polar nuclei) is completed, the post-fertilization changes start. The zygote (formed by the fusion of male gamete & egg) divides periclinal into 2 cells- basal cell & terminal cell. The basal cell undergoes cleavage to form a suspensor (a linear group of cells) while the terminal cell divides further to form an embryo. The embryo further divides and differentiates via 3- consecutive developmental stages. Globular stage- The first stage is- globular stage (cells divide to form a globule-like structure). Heart stage- The second stage is heart stage -where the cells divide to form a heart-shaped embryonal stage. Torpedo stage- the torpedo stage is the third and the final is achieved. Here, the cells divide & differentiate into the following:Radicle- radicle forms the root meristem;Plumule- plumule i.e., shoot meristem and;Cotyledon- The number of cotyledons is 1 in monocotyledonous plants and 2 in dicotyledonous plants.As soon as the process of Post-fertilisation changes starts, the calyx (sepals), corolla (petals), and androecium shed off. Only the ovary remains attached to the flower.
