An epicotyl is important for the beginning stages of a plant's life. It is the region of a seedling stem above the stalks of the seed leaves of an embryo plant. It grows rapidly, showing hypogeal germination, and extends the stem above the soil surface. A common misconception is that the epicotyl, being closer to the apex of the plant, is the first part to emerge after germination - rather, the hypocotyl, the region of the stem between the point of attachment of the cotyledons and the root - forms a hook during hypogeal germination and pushes out of the soil, allowing the more delicate tissues of the plumules and apical meristem to avoid damage from pushing through the soil. The epicotyl will expand and form the point of attachment of the
shoot apex and leaf primordia or "first true leaves". Cotyledons may remain belowground or be pushed up aboveground with the growing stem depending on the plant species in question.
In
plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants.
Plant physiologists study fundamental processes of plants, such as photosynthesis, respiration, plant nutrition, plant hormone functions, tr ...
, the epicotyl is the embryonic shoot above the
cotyledon
A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow",
gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
s. In most plants the epicotyl will eventually develop into the leaves of the plant. In
dicots, the
hypocotyl
The hypocotyl (short for "hypocotyledonous stem", meaning "below seed leaf") is the stem of a germinating seedling, found below the cotyledons (seed leaves) and above the radicle (root).
Eudicots
As the plant embryo grows at germination, it send ...
is what appears to be the base stem under the spent withered cotyledons, and the shoot just above that is the epicotyl. In
monocot
Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are flowering plants whose seeds contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. A monocot taxon has been in use for several decades, but ...
plants, the first shoot that emerges from the ground or from the
seed
In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
is the epicotyl, from which the first shoots and leaves emerge.
Lengthening of the epicotyl is thought to be controlled by the phytochrome photoreceptors.
See also
*
Hypocotyl
The hypocotyl (short for "hypocotyledonous stem", meaning "below seed leaf") is the stem of a germinating seedling, found below the cotyledons (seed leaves) and above the radicle (root).
Eudicots
As the plant embryo grows at germination, it send ...
*
Radicle
In botany, the radicle is the first part of a seedling (a growing plant embryo) to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil (the shoot emerges from t ...
*
Plumule
External links
* "epicotyl." A Dictionary of Biology. 2004. Encyclopedia.com. 3 Dec. 2015
Plant morphology