What Is Epigeal?

 Epigeal germination is a type of germination whereby the seed leaves or the cotyledons are brought on to the surface or above the soil along with the shoot during germination. This is usually due to rapid elongation and curved-like shape of the hypocotyl. This change in the shape or curvature of the hypocotyl allows the seed leaves or the cotyledons to come above the surface of the soil.

 The hypocotyl is the part of the stem of an embryo plant beneath the stalk of the cotyledons. After the cotyledons have come above the soil surface, the hypocotyl straightens resulting to falling off, of seed coat and with time the appearance of the cotyledons change to green. Now, the resultant plant structure (epicotyl) eventually matures and gives rise to mature green leaves and with time the cotyledons fall off.  The main function of cotyledons in Epigeal germination is storage of food. They also undergo photosynthesis and produce food for the development of the embryo.

Generally dicot seeds show Epigeal type of germination and in this regard, Epigeal seed germination can be observed in onion, castor, Alisma, papaya and bean.

What You Need To Know About Epigeal Germination

• Epigeal germination is a type of germination whereby the seed leaves or the cotyledons are brought on to the surface or above the soil along with the shoot during germination.
• In Epigeal germination, the terminal part of the hypocotyl is curved to protect the plumule from the friction of the soil.
• The cotyledons in Epigeal germination are brought out of the soil by the excessive growth of the hypocotyl.
• The plumule comes out of the seed coat by the elongation of the hypocotyl.
• The energy for growth is primarily derived from cotyledon.
• Epicotyl is short in plants that show Epigeal germination.
• The cotyledons turn green, act as the first leaves of the plant and take part in photosynthesis.
• The plumule remains enclosed and protected by cotyledons till it comes out of the soil.
• Generally dicot seeds show this type of germination (Epigeal).
• Epigeal germination occurs in beans, Alisma, onion and, papaya, castor.

What Is Hypogeal?

Hypogeal germination is a type of germination whereby the seed leaves or the cotyledons remain below the soil surface during germination. This is due to the rapid development and growth in length of the epicotyl.

After development and growth in length of the epicotyl, the epicotyl assumes a curved curvature; this causes the plumule to emerge above the soil surface while the cotyledons remain below the soil surface. The plumule grows in length rapidly in this type of germination and it eventually ruptures the coleoptiles and undergoes further growth. The ruptured plumule grows to the radical and is replaced by the root system. In Hypogeal germination, the terminal part of the epicotyl is curved in order to reduce damage to plumule by friction from soil particles.

Generally monocot seeds show hypogeal germination. In this regard, hypogeal germination can be observed in arum seeds, Coconut, water lily and maize seeds.

What You Need To Know About Hypogeal Germination

• Hypogeal germination is a type of germination whereby the seed leaves or the cotyledons remain below the soil surface during germination.
• In Hypogeal germination, the terminal part of the epicotyl is curved in order to reduce damage to plumule by friction from soil particles.
• The hypocotyl in hypogeal germination does not elongate much. Instead, the epicotyl grows and takes the plumule above the soil.
• The plumule comes out of the seed coat by the elongation of epicotyl.
• The energy for growth is primarily derived from the endosperm.
• The epicotyl is long in plants that show hypogeal germination.
• The cotyledons do not play any role in photosynthesis.
• The plumule does not remain enclosed and protected by cotyledons till it comes out of the soil.
• Generally monocot seeds show hypogeal germination.
• Hypogeal germination occurs in coconut, pea, gram, water lily, arum and maize.

Also Read: Difference Between Phototropism And Photoperiodism

Difference Between Epigeal And Hypogeal Germination In Tabular Form

Similarities Between Epigeal And Hypogeal Germination

• Both are described by the relative position of the cotyledons to the soil during germination.
• Both are the two main methods of germination.
• In both methods water is an essential component.
• In both Epigeal and hypogeal germination, the epicotyl is curved to reduce damage to the plumule.

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