Germination is the process by which a seed develops into a new plant under favorable environmental conditions. Among flowering plants, there are two primary types of germination: epigeal germination and hypogeal germination. These two types differ in the way the seedling emerges from the soil and in the position of the cotyledons during early growth. Understanding the differences between epigeal and hypogeal germination is important in plant biology, as it helps explain how various species adapt their growth strategies to their environment.
Table of Contents
- Differences Between Epigeal and Hypogeal Germination
- What is Epigeal Germination?
- Characteristics of Epigeal Germination
- Examples of Epigeal Germination
- What is Hypogeal Germination?
- Characteristics of Hypogeal Germination
- Examples of Hypogeal Germination
What is Epigeal Germination?
Epigeal germination is a type of germination where the cotyledons (seed leaves) come above the soil surface as the seedling grows.
Characteristics of Epigeal Germination
- The hypocotyl (stem section below the cotyledons) grows and pushes the cotyledons above the soil.
- The cotyledons turn green and temporarily act as photosynthetic leaves.
- The seedling depends on the cotyledons for nutrients until the first true leaves develop.
Examples of Epigeal Germination
- Beans (Phaseolus vulgaris)
- Castor (Ricinus communis)
- Sunflower (Helianthus annuus)
- Pumpkin (Cucurbita pepo)
Example Explanation: In beans, the cotyledons rise above the ground and help in early photosynthesis.
What is Hypogeal Germination?
Hypogeal germination is a type of germination where the cotyledons remain below the soil surface as the seedling grows.
Characteristics of Hypogeal Germination
- The epicotyl (stem section above the cotyledons) grows while the hypocotyl remains short.
- The cotyledons stay underground and provide nutrients to the growing seedling.
- The first leaves (true leaves) emerge from the soil and take over photosynthesis.
Examples of Hypogeal Germination
- Pea (Pisum sativum)
- Maize (Zea mays)
- Mango (Mangifera indica)
- Gram (Cicer arietinum)
Example Explanation: In maize, the cotyledons stay underground, and the seedling grows above the soil using stored nutrients.
Key Differences Between Epigeal and Hypogeal Germination
| Feature | Epigeal Germination | Hypogeal Germination |
|---|---|---|
| Cotyledon Position | Above the soil | Below the soil |
| Growth Type | Hypocotyl elongates, lifting the cotyledons | Epicotyl elongates, cotyledons stay underground |
| Cotyledon Function | Acts as early photosynthetic leaves | Stores nutrients for seedling growth |
| Examples | Beans, Sunflower, Pumpkin | Pea, Maize, Mango |
| Seed Type | Common in dicot plants | Common in monocot plants |
READ ALSO Full article on – Types of Germination, process and conditions for germination
Conclusion
Epigeal and hypogeal germination are two ways in which seeds sprout and grow into plants. Epigeal germination lifts the cotyledons above the soil, while hypogeal germination keeps them underground. Both types of germination have advantages depending on the plant species and environmental conditions.
Revision Questions and Answers
1. What is germination?
Answer: Germination is the process by which a seed develops into a new plant under suitable conditions.
2. What is the main difference between epigeal and hypogeal germination?
Answer: In epigeal germination, the cotyledons rise above the soil, while in hypogeal germination, they remain underground.
3. Name two plants that show epigeal germination.
Answer: Beans and Sunflower.
4. Name two plants that show hypogeal germination.
Answer: Pea and Maize.
5. Which part of the seedling elongates in epigeal germination?
Answer: The hypocotyl elongates in epigeal germination, pushing the cotyledons above the soil.
6. Which part of the seedling elongates in hypogeal germination?
Answer: The epicotyl elongates in hypogeal germination, while the cotyledons remain underground.