Q.Cotyledon of maize grain is called

Plant Seed Structure – From Intuition to Precision

Think of a seed as a survival pod. A plant cannot move, so it must send its offspring away — into wind, water, or an animal's gut — to find new ground. But the journey is harsh: no soil, no water, no sunlight. The seed must carry everything it needs to stay alive and then restart growth when conditions are right.

That is the seed's entire job: a baby plant, packed with food, inside a protective shell, waiting for the right moment.

The Three Essential Parts

Every seed, from a tiny mustard seed to a giant coconut, has three layers:

1. Seed Coat – the outer armour
2. Embryo – the baby plant itself
3. Endosperm / Cotyledons – the packed lunch

Let's look at each.

1. Seed Coat (Testa)

The seed coat is a tough, often hard outer layer. It protects the embryo from physical damage, microbes, and drying out. In some seeds it is papery (like in a peanut), in others it is rock-hard (like in a date seed). There is usually a tiny scar called the hilum — the point where the seed was attached to the mother plant. Next to it is a small pore, the micropyle, through which water enters to trigger germination.

2. Embryo – The Baby Plant

The embryo is a miniature, dormant plant. It has three parts:

• Radicle – the future root. It grows downward first.
• Plumule – the future shoot (stem + first leaves). It grows upward.
• Cotyledons – the "seed leaves". These are not true leaves; they are food-storage or food-absorption organs.

The region between radicle and plumule is the hypocotyl (the stem of the embryo).

3. Endosperm and Cotyledons – The Packed Lunch

The embryo cannot photosynthesise until it reaches light. So the seed stores food — starch, proteins, oils — either in a special tissue called endosperm or inside the cotyledons themselves.

• Endospermic seeds (e.g., maize, wheat, castor) have a large endosperm that surrounds the embryo. The cotyledons are thin and absorb food from the endosperm.
• Non-endospermic seeds (e.g., pea, bean, groundnut) digest the endosperm during development and store all food inside the cotyledons, which become thick and fleshy.

A Concrete Example: The Bean Seed

Take a kidney bean that has been soaked overnight. Peel off the brown seed coat. Inside you find two large, cream-coloured halves — these are the cotyledons. Between them, at one end, is a tiny white structure: the embryo. The pointed end is the radicle; the fuzzy end is the plumule. There is no endosperm left — the cotyledons are the packed lunch.

Now split the cotyledons apart. You see the embryo clearly: a miniature plant, complete with root and shoot, curled up and waiting.

--- …