Structure of Seeds
Before moving onto the ‘Structure of seeds’ you should learn about the seed. The seed is a mature and ripened ovule of a flower that is formed after fertilization. It stores food material for the nourishment of the embryo during germination. The seed coat protects the embryo from mechanical damage. Examples: Bean, pea, etc.
- The fruit is an enlarged, matured or ripened ovary. It protects the seed and helps in seed dispersal. Examples: Mango, pea pod etc.
- Grain is actually a fruit in which the fruit wall and the seed coat are fused together to form a protective layer. Examples: Maize, wheat etc.
Kinds of Seeds
- Monocotyledonous seeds: Consist of only one cotyledon. Examples: Maize, grass etc.
- Dicotyledonous seeds: Consist of two cotyledons. Examples: Pea, gram, bean etc.
- Small seeds: Very tiny and not visible to the naked eye. Examples: Poppy, orchid etc.
- Large seeds: Bigger and easily visible to the naked eye. Examples: Watermelon, pumpkin, mango etc.
- Largest seeds: Biggest and double the size of large seeds. Examples: Coconut, double coconut etc.
- Albuminous/endospermic seeds: The endosperm is large, thick and fleshy. It serves as the food source for the developing embryo.
- Dicot albuminous seeds: Poppy, custard apple, muskmelon, fenugreek etc.
- Monocot albuminous seeds: Cereals, millets, palm, onion etc.
- Exalbuminous/non-endospermic seeds: The cotyledons store food and become thick and fleshy.
- Dicot exalbuminous seeds: Gram, pea, mango, mustard, soya bean etc.
- Monocot exalbuminous seeds: Orchid, Amorphophallus, Vallisneria etc.
Differences between Bean seed and Maize grain
| Parts | Bean Seed | Maize Grain |
| Cotyledons | Two | One |
| Endosperm | Absent | Large |
| Embryo | Large | Small |
| Plumule leaves | Folded | Rolled |
| Plumule | Large | Very small |
| Hilum | Visible | Not visible |
| Micropyle | Visible | Not visible |
| Seed arrangement | Separate, contained in fruit called pod | No separate seed. Seed wall and fruit wall is fused to form a single grain. |
Germination
The process in which the embryo emerges out of the seed by rupturing the seed coat, leading to the formation of a seedling is called germination.
Conditions necessary for Germination ~ Read here
Types of Germination ~ Read here
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