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As we walk around the garden, we come across the different types of new seedlings, and small plants with tender leaves and stem arising from the soil. Have you ever wondered, how these new plants grow and how seeds are dispersed? Here in this article, let us learn in brief about the seeds and how they are dispersed.
What is a Seed?
Seeds are the unit of the reproduction of a flowering plant that is capable to develop into a single plant. In some species of plant, like walnuts, groundnuts, and chickpeas, seeds are also used as sources of food.
A fully grown and developed seed has three primary parts: the embryo, endosperm, and seed coat. The plumule is present in the seed embryo, which develops into a new plant.
Also, read: Parts of a Seed
What is Seed Dispersal?
Seed Dispersal is an adaptive mechanism in all seed-bearing plants, participating in the movement or transport of seeds away from their parent plant to ensure the germination and survival of some of the seeds to adult plants. There are many vectors to transport the seed from one place to another.
Also, read: Formation and Dispersal of Seeds
Types of Seed Dispersal
There are different ways in which seeds from its parent plant is dispersed. These include:
Seed Dispersal by Wind
The wind is the natural and fundamental means of seed dispersal in the plant kingdom. This process of dispersal is mainly seen in those plants which bear very light seeds. The seeds of the orchid plant, dandelions, swan plants, cottonwood tree, hornbeam, ash, cattail, puya, willow herb, are all examples of plants whose seed are dispersed by the wind.
Seed Dispersal by Water
In this method of seed dispersal, seeds float away from their parent plant. These are mainly seen in those plant which lives in water or nearby the water bodies like beaches, lakes, ponds etc. Coconut, palm, mangroves, water lily, water mint, are a few examples of plants whose seed are dispersed by the water.
Seed Dispersal by Animal and Birds
There are different ways in which animals and birds disperse the seeds.
Few animals and birds are attracted to bright colourful fruits. They eat the entire fruit and only the juicy part is digested by their system and the seed are excreted out in the form of their dropping, which forms into new plants. Blackberry, cherry, tomato and apple seeds are dispersed in this way.
A few species of squirrels collect nuts from different plants like acorns and bury them under the soil as they store food for the winter season and often forget the place where they have previously buried them and the seeds grow into new trees.
There are a few plants which bear seeds with hooks. Burdock plant is an example of this type of plant species. The seed of these plants catches on the fur of animals and are carried away to different places, far from their parent plants.
Dates, rambutan, sea grapes, sea holly, tamarind, raspberry, sunflower, tomatoes are a few examples of plants whose seeds are dispersed by animals and birds.
Seed Dispersal by Gravity
Gravity is a force of attraction that exists among all the objects in the universe.
As the fruits from the tree fall on the ground due to the force of attraction, they sometimes roll down to some smaller distance, get buried in the soil after a few days and germinate into a new plant.
In certain cases, fruits which do not have very hard seed coat may crack and open after falling down from a height, which leads to a better dispersion of seeds.
In some cases, the fallen fruit is carried by other agents like water, wind, birds or animal and helps in the dispersion of seeds.
Apples, Commelina, canna, coconuts, calabash, passion fruit are a few examples of plants whose seeds are dispersed by Gravity – A force of attraction.
Seed Dispersal by Explosions
Explosions in fruits literally refer to bursting with all its energy. In this case, as the fruits get ripened, it shoots out its seeds into the external environment. This type of seed dispersal is mainly seen in those plants having pods.
Okra, Lupins, gorse, and broom are a few examples of plants whose seeds are dispersed by Explosions. Pea and bean plants also have pods and the seeds burst out when they ripen and pod has dried.
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