Hypogeal Germination Meaning
Germination refers to a fundamental process in which we grow the sown plant seeds into younger plants or seedlings. Based on the growing conditions and the cotyledons' fate, there are two types of germination processes, as follows:
Epigeal germination
Hypogeal germination
This article is essential for the Biology students to get a brief idea about germination, its types, and hypogeal germination. It covers all the fundamentals of the concepts and includes some FAQs related to the examinations to assure the students' best practice and understanding.
Define Hypogeal Germination
A hypogeal germination is a form of seed germination that occurs mainly for both monocot and dicot seeds. The cotyledons stay inside the soil due to quicker growth and development in the epicotyl's length. Hypogeal germination is derived from an ancient Greek word, referring to the meaning 'below ground'. Here is a description of the hypogeal germination process:
Cotyledons :
A significant part of the embryo of the seed stays under the soil.
Plumule:
The rudimentary shoot tip that rises from the seed embryo grows above the ground.
Plumule rises and pushes itself upwards.
This process continues with epicotyl – the seed system that stays above the cotyledon and rapidly elongates its structure and shape.
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What is the Hypogeal Germination Process?
After the epicotyl's length grows and develops ultimately, it assumes a curved curvature, causing the plumule to rise above the soil surface and pushing the cotyledons to stay below the surface. In these types of germination, the plumule rapidly grows in length and then eventually ruptures the coleoptiles while undergoing further growths.
The ruptured plumule then grows into radical, and the root system then replaces it. In this germination, the terminal part of epicotyls is curved for reducing damage to plumule by friction due to the soil particles.
Hypogeal Germination Seed Examples
Here are some hypogeal germination examples:
Among the dicotyledons, pea, gram, and groundnut are some prominent examples.
In monocotyledons, maize, coconut, rice, and wheat are some common examples.
Pros and Cons Related to Hypogeal Germination
The benefit of hypogeal germination is that the plant or the seedlings are protected from early grazing in this process. In contrast, the disadvantage of hypogeal germination is that in this process, the plant cannot start synthesizing its food or photosynthesize until the true leaves appear entirely.
Key Points Necessary to Understand About Hypogeal Germination
Hypogeal germination is among the prominent types of germination in which the seed leaves or cotyledons stay under the soil surface during the entire germination process.
In this, the terminal part of the epicotyl stays curved for reducing the damage to the plumule due to the friction from soil particles.
In hypogeal germination, hypocotyls do not elongate more. Instead of that, the epicotyl grows while keeping the plumule above the soil.
With the elongation of the epicotyls, the plumule emerges out of the seed coat in the process.
In this germination, the energy for growth is mainly derived from the endosperm.
Epicotyl is comparatively more extended in the plants, which show hypogeal germination.
Cotyledons do not appear as playing any significant role during photosynthesis.
Plumule does not always stay enclosed and protected by the cotyledons until it emerges out of the soil.
Mostly, the monocot seeds are the ones that show hypogeal germination prominently.
Hypogeal germination occurs in several plants, including maize, arum, water lily, gram, pea, and coconut.
This is all about hypogeal germination and its examples. Understand the difference of this germination process with the rest and focus on its traits to grab hold of the concept.
FAQs on Hypogeal Germination
1. What exactly is hypogeal germination?
Hypogeal germination is a type of seed sprouting where the seed leaves, or cotyledons, remain below the ground. In this process, the part of the stem above the cotyledons, called the epicotyl, elongates and pushes the young shoot (plumule) up through the soil.
2. What is the main difference between hypogeal and epigeal germination?
The key difference lies in the position of the cotyledons after germination. In hypogeal germination, the cotyledons stay underground. In epigeal germination, the part of the stem below the cotyledons (the hypocotyl) elongates, lifting the cotyledons above the ground, where they often turn green and act like the first leaves.
3. Can you give some examples of plants that show hypogeal germination?
Yes, several common plants use this method. Some well-known examples include:
- Pea
- Gram (Chickpea)
- Maize (Corn)
- Mango
- Coconut
4. What are the main steps involved in hypogeal germination?
The process of hypogeal germination follows a few key stages:
- Imbibition: The seed absorbs water, which activates the embryo.
- Radicle Growth: The radicle emerges from the seed coat and grows downwards to form the primary root system.
- Epicotyl Elongation: The epicotyl grows upwards, forming a hook shape to protect the delicate plumule.
- Shoot Emergence: The epicotyl pulls the plumule above the soil surface and then straightens out. The first leaves unfold and begin photosynthesis.
5. Why do some plants keep their cotyledons underground during germination?
Plants use hypogeal germination as a protective strategy. By keeping the cotyledons underground, the seed's primary food reserve is shielded from harsh weather, foraging animals, and physical damage. This is especially useful for seeds with large, fleshy cotyledons that contain enough energy to fuel initial growth without needing to perform photosynthesis.
6. What is the role of the cotyledons in hypogeal germination if they don't photosynthesise?
In hypogeal germination, the primary role of the cotyledons is to act as a storage organ. They are packed with stored food (like starch, proteins, and oils) that provides all the necessary energy for the embryo to grow its roots and push its first shoot up into the sunlight. Once the true leaves are formed, the plant can start making its own food.
7. How does the epicotyl's hook-like shape help the new plant?
The hook shape of the epicotyl is a clever mechanical adaptation. As the epicotyl pushes upwards, the tough, bent part of the hook leads the way, breaking through the soil. This protects the extremely delicate plumule (the developing shoot tip and first leaves) from being torn or damaged by friction with soil particles. Once it is safely above ground, the hook straightens out.
