There are three types of germination of seeds, those are: -
Now let us go for some details, which will be very easy to understand about the types of germination of seeds.
Hypogeal or Hypogeous types of germination
What is Hypogeal germination?
This is one of the types of germination in which, the cotyledon or cotyledons remain inside the seed coat and do not come above the level of soil, is called hypogeal germination.
Characteristics of Hypogeal types of germination
i) The seed germinates in situ, i.e., the original position of the cotyledons is not distorted in the soil.
ii) The radicle is the first structure to appear by piercing the seed coat near the micropyle.
iii) The radicle grows for some time and then bends into the soil.
iv) The plumule comes out next by the elongation of the epicotyls and grows upward above the level of the soil.
Examples of Hypogeal types of germination
a) Monocotyledonous exalbuminous seeds like arum.
b) Dicotyledonous exalbuminous seeds like gram, mango and pea.
c) Monocotyledonous, albuminous seeds like water-lily.
d) Monocotyledonous, albuminous seeds like maize, wheat and rice.
Epigeal or Epigeous types of germination
What is Epigeous germination?
This is one of the types of germination, in which the cotyledon or cotyledons come out of the seed coatabove the level of soil, is called epigeal germination.
Characteristics of Epigeal or Epigeous types of germination
i) The radicle is the first structure to emerge, which heads into the soil in the form of hypocotyl.
ii) The growth and germination of the plumule is delayed.
iii) The hypocotyl forms a loop and then straightens itself to raise the seed above the soil surface.
iv) The seed splits to produce the two cotyledons.
v) The cotyledons are held above the ground and they extend to produce the 2 cotyledonary leaves.
vi) The development of the shoot takes place after that.
Examples of Epigeous types of germination
a) Monocotyledonus albuminous seed like onion.
b) Dicotyledonous albuminous seed like castor.
c) Monocotyledonous exalbuminous seed like Alisma.
d) Dicotyledonous exalbuminous seeds like bean, tamarind and gourd.
Vivipary or Viviparous types of germination
What is Viviparous germination?
This is one of the types of germination in which the seed instead of being liberated from the fruit, germinates inside it, while the fruit is attached to the parent plant.
Characteristics of Vivipary or Viviparous types of germination
i) They are usually observed in mangrove plants growing in saline soil (physiologically dry soil).
ii) This is an important halophytic adaptation.
iii) The embryo develops rapidly without any resting period.
iv) The embryo grows out of the seed and fruit while the fruit is hanging from the parent plant.
v) The hypocotyl of the embryo grows and protrudes to a considerable length from the fruit.
vi) When the fruits get detached from the parent plant, the hypocotyl gets implanted vertically in the soft soil and the secondary roots develop from it.
Example of Viviparous types of germination
Mangrove plants like Rhizophora, Ceriopsare the examples of this type of germination.