Difference Between Epigeal And Hypogeal Germination

May 2023 · 5 minute read

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

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

Also Read: Difference Between Phototropism And Photoperiodism

Difference Between Epigeal And Hypogeal Germination In Tabular Form

BASIS OF COMPARISONEPIGEAL  GERMINATIONHYPOGEAL GERMINATION
DescriptionEpigeal 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.  Hypogeal germination is a type of germination whereby the seed leaves or the cotyledons remain below the soil surface during germination.  
Terminal Part Of Hypocotyl & EpicotylThe terminal part of the hypocotyl is curved to protect the plumule from the friction of the soil.  The terminal part of the epicotyl is curved in order to reduce damage to plumule by friction from soil particles.
Effect Of Elongation Of The Hypocotyl & EpicotylThe cotyledons in Epigeal germination are brought out of the soil by the excessive growth of the hypocotyl.  The hypocotyl in hypogeal germination does not elongate much. Instead, the epicotyl grows and takes the plumule above the soil.  
PlumuleThe plumule comes out of the seed coat by the elongation of the hypocotyl.  The plumule comes out of the seed coat by the elongation of epicotyl.  
Energy For GrowthThe energy for growth is primarily derived from cotyledon.  The energy for growth is primarily derived from the endosperm.  
Length Of The EpicotylEpicotyl is short in plants that show Epigeal germination.  The epicotyl is long in plants that show hypogeal germination.  
CotyledonsThe cotyledons turn green, act as the first leaves of the plant and take part in photosynthesis.  The cotyledons do not play any role in photosynthesis.  
PlumuleThe plumule remains enclosed and protected by cotyledons till it comes out of the soil.  The plumule does not remain enclosed and protected by cotyledons till it comes out of the soil.  
ProminenceGenerally dicot seeds show this type of germination (Epigeal).  Generally monocot seeds show hypogeal germination.  
PresenceEpigeal germination occurs in beans, Alisma, onion and, papaya, castor.  Hypogeal germination occurs in coconut, pea, gram, water lily, arum and maize.  

Similarities Between Epigeal And Hypogeal Germination

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