Embryology of angiosperms

Embryology is the study of the development of embryos, which are the earliest stages of an organism's development. Angiosperms, or flowering plants, have a unique reproductive system that involves the production of flowers, fertilization, and the development of seeds. Here is an overview of the embryology of angiosperms:

1. Flower Structure: The reproductive structure of angiosperms is the flower. A typical flower consists of four main parts: sepals, petals, stamens, and carpels. The stamens are the male reproductive organs that produce pollen, while the carpels are the female reproductive organs that contain the ovules.

2. Pollination: Pollination is the transfer of pollen from the anthers (the part of the stamen that produces pollen) to the stigma (the receptive surface of the carpel). Pollination can occur through various mechanisms, including wind, water, or animal pollination.

3. Double Fertilization: Angiosperms have a unique process called double fertilization. When a pollen grain reaches the stigma, it forms a pollen tube that grows down through the style and into the ovary. The pollen tube delivers two sperm cells to the ovary. One sperm cell fertilizes the egg cell, forming the zygote, which develops into the embryo. The other sperm cell combines with two polar nuclei in the central cell of the ovule, forming the endosperm, which provides nutrients for the developing embryo.

4. Embryo Development: After fertilization, the zygote undergoes a series of divisions to form an embryo. The first division results in a basal cell and a terminal cell. The terminal cell gives rise to the shoot apical meristem (SAM), which develops into the stem, leaves, and flowers, while the basal cell develops into the root system. The embryo develops different tissue layers, including the protoderm (gives rise to the epidermis), ground meristem (forms the ground tissues), and procambium (gives rise to the vascular tissues).

5. Seed Development: As the embryo develops, other structures in the ovary also mature to form a seed. The seed consists of the embryo, endosperm, and seed coat. The seed coat provides protection to the embryo and endosperm. The endosperm serves as a source of nutrients for the developing embryo.

6. Seed Germination: When conditions are favorable, the mature seed can germinate and give rise to a new plant. Germination involves the absorption of water, activation of enzymes, and growth of the embryo. The radicle, which is the embryonic root, emerges first, followed by the shoot.

The embryology of angiosperms is a complex process that ensures the successful reproduction and dispersal of these plants. It plays a crucial role in the formation of seeds, which are vital for the survival and propagation of angiosperm species.