Parts of a Seed and Their Functions
A seed is a structure that encloses the embryo of a plant in a protective outer covering. Under favorable conditions of growth, a seed gives rise to a new plant, using the nutrients stored in them.
The union of the male and female reproductive cells inside the ripened ovule of a flower helps in the formation of seeds in a plant. Different seeds have different sizes, shapes, and colors that participate in the reproduction of flowering plants.
Parts and Structure of a Seed
A typical seed consists of three main parts: 1) seed coat, 2) endosperm, and 3) embryo.
1) Seed Coat
They are the protective outer covering of a seed that is usually hard, thick, and brownish in color. The seed coat is formed from the outer covering of the ovule called the integument. It usually contains two layers: i) testa – the thick outer layer, and ii) tegmen – the delicate inner layer.
A seed coat has the following four parts: a) Micropyle – the small opening present at one end of the seed coat, b) Funiculus – the seed stalk with which the seed is attached to the fruit body, the integument, c) Hilum – the region from which the seed breaks off from the fruit, leaving a scar, and d) Raphe – the base of the funiculus that is fused with the integument.
- Protecting the seed from physical and mechanical damage
- Preventing the seed from germination even under favorable conditions of growth (seed dormancy)
- Preventing the excessive loss of water from the seeds
- Acting as a physical barrier against the entry of parasites
It is a tissue that is rich in oil, starch, and protein. Depending on the presence or absence of endosperm, seeds are of two types:
i) Non-endospermic or exalbuminous seeds – Characterized by the complete absence of the endosperm, such as the seeds of the pea plant, groundnut, and gram.
ii) Endospermic or albuminous seeds – Characterized by the presence of the endosperm, such as the seeds of millets, palms, and lilies.
- Storing of reserve foods that provide nourishment to the developing plant
- Protecting the embryo, the next part of the seed, by acting as the mechanical barrier
What are the Parts of an Embryo of a Seed
- Epicotyl – The tiny shoot of an embryo, from which the entire shoot system develops. The tip of the epicotyl is called plumule.
- Hypocotyl – The stage of transition for the growing shoot and root of the embryo
- Radicle – The tiny root of the embryo
- Cotyledons – They are the leaves of the embryo that provide nourishment to the developing plant. There are two types of cotyledons present in flowering plants: i) monocotyledonous or monocots – embryo with one cotyledon and ii) dicotyledonous or dicots – embryo with two cotyledons.
- Giving rise to a new complete new plant
- Storing food and nourishing the baby plant
Article was last reviewed on Tuesday, October 6, 2020