Seeds – Structure and Germination

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

PartsBean SeedMaize Grain
CotyledonsTwoOne
EndospermAbsentLarge
EmbryoLargeSmall
Plumule leavesFoldedRolled
PlumuleLargeVery small
HilumVisibleNot visible
MicropyleVisibleNot visible
Seed arrangementSeparate, 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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