Flowers and Plants Presentation

Seed Dispersal and Germination

seed dispersal

Seed dispersal is the process by which plants spread their seeds to colonize new areas. It is a crucial step in the plant life cycle as it allows plants to reproduce and survive. It also refers to the movement of seeds away from their parent plant to new areas where they can germinate and grow into new plants.

Types/Methods of seed dispersal

1. Wind dispersal

2. , water dispersal

3. animal dispersal

4. self-dispersal

• ensures the survival and distribution of their offspring.

• facilitates plant colonization of new habitats. Seeds that are dispersed to different locations have a higher chance of finding suitable conditions for germination and growth.

• enhances genetic diversity within and between plant populations.

Uses of seed dispersion

1. Wind dispersal

In this process, seeds have adaptations that help them catch the wind and be carried far away from the parent plant. These adaptations include wings, feathery structures, or hairs. As the wind blows, the seeds are lifted into the air and carried to different locations. This method allows plants to colonize a wide range of environments, as the seeds can travel long distances by wind.

2. water dispersal

Seeds are designed to float on water and move with the current. This method enables plants to reach new habitats, such as other bodies of water or even foreign lands. Some seeds have a protective coat that prevents them from getting damaged by water, allowing them to remain viable during their journey.

Animal dispersal

also known as zoochory, involves animals playing a crucial role in the dispersal of seeds. This method relies on animals either carrying the seeds internally or externally. Some plants have fruits or seeds that are active to animals, who eat them and then pass the seeds through their digestive system. The seeds are then deposited in a different location through the animal's droppings. Other plants have adaptations that allow their seeds to stick to animals' fur or feathers as they brush against them. As animals move, the seeds are carried with them and deposited elsewhere.

Self-dispersal occurs in plants that have mechanisms to disperse their own seeds. These mechanisms are usually triggered by certain environmental conditions or physical forces. For example, some plants have specialized fruit capsules that explode when they dry, flinging the seeds away from the parent plant. Other plants have seed pods that twist and split open when they mature, releasing the seeds. These mechanisms help plants colonize new areas without relying on external agents for seed dispersal.

self-dispersal

Process of seed germination

The process of seed germination involves several key steps. Firstly, the seed absorbs water through its outer seed coat in a process known as imbibition. This triggers the seed to rehydrate and start metabolism. As a result, enzymes become active, initiating the breakdown of starches and other storage compounds within the seed. These compounds provide the necessary nutrients for the developing embryo. Simultaneously, hormones such as gibberellin are produced and promote the elongation of cells, leading to the growth of a root, known as the radicle. Once the radicle is established, it anchors the seedling into the soil. Following this, the stem or shoot emerges, bringing the seedling above the ground where it can access light for photosynthesis.

Seed Germination

Seed germination is the process through which a plant embryo emerges from a seed and begins to grow and develop into a new plant. It is a critical phase in the life cycle of plants, as it marks the transition from a dormant seed to an actively growing organism. Germination is triggered by environmental cues such as moisture, temperature, and light, which activate biochemical reactions within the seed. These reactions lead to the activation of dormant enzymes, the breakdown of stored nutrients, and the emergence of the embryo's first root and shoot.

What are Epigeal and Hypogeal?

Epigeal and hypogeal are terms that describe different types of germination in plants. Germination is the process by which a seed begins to grow into a new plant. Epigeal germination refers to the type of germination where the cotyledons (the embryonic leaves) emerge above the ground. In this type of germination, the stem elongates rapidly, bringing the cotyledons and leaves above the soil surface. Epigeal germination is commonly observed in dicotyledonous plants, such as beans and peas. In contrast, hypogeal germination is a type of germination where the cotyledons remain below the ground. In this process, the stem grows minimally, and the cotyledons stay submerged and serve as food storage for the growing seedling. True leaves are the first to emerge and are initially above the cotyledons, pushing them out of the soil. Hypogeal germination is typically seen in monocotyledonous plants.

Seed dispersal and germination

Similarities and Differences

Seed dispersal refers to the movement or transportation of seeds away from the parent plant. The main aim of seed dispersal is to prevent overcrowding and competition for resources among offspring. Many plants have evolved different methods to disperse their seeds, such as wind dispersal, water dispersal, animal dispersal, and self-dispersal. Similarly, germination is the process by which a seed sprouts and develops into a new plant. It involves the absorption of water, activation of enzymes, and the growth of a root and shoot system. Both seed dispersal and germination are essential for plants to establish themselves in new locations and ensure the survival and genetic diversity of the species.Despite their similarities, seed dispersal and germination also have distinct characteristics. Seed dispersal occurs before germination and is mainly carried out by external agents like wind, water, or animals. It involves the movement of seeds from the parent plant to a new location. Germination, on the other hand, occurs after a seed reaches its optimal location for growth where it can receive favorable conditions for its development. It is primarily an internal process triggered by the interaction between the seed and its environment, such as moisture, temperature, and oxygen availability. Germination leads to the growth of roots and shoots from the seed, establishing a new plant.

Hypogeal and Epigeal

Hypogeal and epigeal are two terms commonly used in biology to describe different types of plant germination. These terms refer to the way plants emerge from the soil during their early stages of growth. While both hypogeal and epigeal germination involve the emergence of the plant from a seed, there are several key similarities and differences between these two processes. Firstly, both hypogeal and epigeal germination involve the initial sprouting of a plant from a seed. However, the main difference lies in the way the cotyledons, the seed leaves, emerge from the soil. In hypogeal germination, the cotyledons remain below the soil surface, while the epicotyl pushes above the soil. This means that in hypogeal germination, the seedlings do not rely on the energy stored in the cotyledons for their early growth, as photosynthesis has not yet begun.

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