Epicotyl and Hypocotyl – Class 12 | Chapter – 2 | Biology Short Notes Series PDF

Epicotyl and Hypocotyl: Epicotyl is the first part of the plant that emerge after the germination, where as it is important in the beginning stage of the plant life, whereas hypocotyl is the structure that can be observed in the seedling after the germination.

Epicotyl

  • It is the region present in the seedling, which is present above and stalks the early formed leaves of an embryo plant.
  • To say simply, in the physiology of the plants, epicotyl is the embryonic shoot which is present above the plants.
  • So in almost all the plants, this structure finally develops into leaves of the plants.
  • This epicotyl in the dicot seeds usually show hypogeal germination, and this structure extends the forming stem above the surface of the soil.
  • Generally this epicotyl ends with plumule.

Hypocotyl

  • It is the region on the stem, where it is present between the point of attachment of the cotyledons of the dicots and the roots
  • Hypocotyl is considered as a base stem which is present within the cotyledon, and shoots above the epicotyl.
  • It forms a hook during the hypogeal germination, and it generally ends as a radicle.
  • The hypocotyl in the monocots, grows out several inches and forms a green color leaf like structure.
  • It is the transition zone between root and the shoot.

Difference Between Epicotyl and Hypocotyl

Hypocotyl Epicotyl
  • It’s the section of the embryonal axis between the radicle and the cotyledons’ attachment site.
  • The segment of the embryonal axis between the plumule and the cotyledons is known as the plumule-cotyledon axis.
  • It is a crucial component of the embryonic root system.
  • It’s a crucial component of the embryonic shoot system.
  • The hypocotyl is situated between the radicle and the node of the cotyledons.
  • The epicotyl, on the other hand, is located between the cotyledon node and the plumule.
  • The purpose of hypocotyl extension is to remove the cotyledon from the earth.
  • The rationale for the extension of the epicotyl is to maintain the cotyledons in the soil.
  • It terminates with the radicle
  • It terminates with the plumule
  • Hypocotyl lifts the seed above the earth during epigeal germination.
  • Epicotyl pushes the plumule above the earth during hypogeal germination.

 


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