Seed Structure — Definition

Definition

Imagine a tiny, self-contained package that holds everything needed to grow a new plant – that's essentially what a seed is! It's like a miniature survival kit for a baby plant. A seed is formed from an ovule after it gets fertilized by pollen. Inside this protective package, there are three main components:

1
The Seed Coat: — This is the outermost layer, acting like the skin or shell of the seed. Its primary job is protection. It shields the delicate inner parts from physical damage, dehydration, and even attack by fungi or insects. Think of it as the armor of the seed. The thickness and texture of the seed coat can vary greatly, from the hard shell of a coconut to the thin, papery covering of a peanut.

1
The Embryo: — This is the actual 'baby plant' inside the seed. It's a miniature, undeveloped plant that has all the basic parts of a mature plant, but in a very compact form. The embryo consists of a few key structures:

* Radicle: This is the embryonic root, which will be the first part to emerge from the seed during germination, anchoring the seedling and absorbing water and nutrients. * Plumule: This is the embryonic shoot, which will develop into the stem and leaves of the new plant.

* Cotyledons: These are the 'seed leaves'. Their main function is to store food or to help absorb food from a separate storage tissue called the endosperm. Plants are broadly classified into monocots (one cotyledon) and dicots (two cotyledons) based on the number of these seed leaves.

* Embryonal Axis: This is the central axis to which the radicle, plumule, and cotyledons are attached.

1
Food Reserves: — The embryo needs energy to start growing before it can make its own food through photosynthesis. This energy comes from stored food reserves within the seed. These reserves are typically in the form of carbohydrates (like starch), fats (oils), and proteins. In some seeds, like castor, this food is stored in a specialized tissue called the endosperm. These are called endospermic or albuminous seeds. In other seeds, like beans or peas, the food is stored directly within the large, fleshy cotyledons, and the endosperm is either absent or very reduced. These are called non-endospermic or exalbuminous seeds.

So, in essence, a seed is a marvel of biological engineering, designed for survival and propagation, ensuring the continuity of plant life by providing a protected and nourished start for the next generation.