Explain the types of germination in detains with examples
There are three main types of germination: epigeal germination, hypogeal germination, and vivipary. Each type differs in how the cotyledons (seed leaves) emerge and grow after the seed has started to sprout.
1. Epigeal germination: In this type, the cotyledons emerge above the ground after the seed has germinated. The epicotyl (the region of the embryo above the cotyledons) elongates and raises the cotyledons and plumule (embryonic shoot) above the soil surface. Examples of plants that exhibit epigeal germination include sunflowers, peas, beans, and tomatoes.
2. Hypogeal germination: In hypogeal germination, the cotyledons remain below the soil surface as the epicotyl grows upward. The cotyledons stay within the seed coat, supplying nutrients to the seedling until it is strong enough to sustain itself. Examples of plants that undergo hypogeal germination include corn (maize), peanuts, and cucumbers.
3. Vivipary: Vivipary is a unique type of germination where the embryo begins to grow while still inside the fruit, rather than waiting to be dispersed as a seed. The seedling then emerges from the fruit, and roots directly into the ground. This phenomenon is often observed in mangroves, where the germinated seeds develop into seedlings while still attached to the parent tree. Other plants that demonstrate vivipary include certain cacti and some tropical fruit trees.
These various types of germination ensure the successful sprouting and establishment of plants, allowing them to grow and reproduce in diverse environments.