The correct answer is option (4) -All of the above
Embryo develops at the micropylar end of the embryo sac where the zygote is situated. Most zygotes divide only after certain
amount of endosperm is formed. This is an adaptation to provide assured nutrition to the developing embryo. Though the seeds differ greatly, the early stages of embryo development (embryogeny) are similar in both monocotyledons and dicotyledons. The zygote gives rise to the proembryo and subsequently to the globular, heart-shaped and mature embryo.
The developing stages of an embryo in angiosperms are:
- Proembryo: This is the earliest stage of embryo development, and it is characterized by a small group of cells that are dividing rapidly.
- Globular embryo: This stage is characterized by a spherical shape, and it is the stage at which the embryo begins to develop its basic body plan.
- Heart-shaped embryo: This stage is characterized by a heart-shaped cotyledon, and it is the stage at which the embryo begins to develop its vascular system.
- Torpedo-shaped embryo: This stage is characterized by a torpedo-shaped cotyledon, and it is the stage at which the embryo is ready to germinate.
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