BIOLO

GY
PROJEC
Seed Dispersal
Sradha Ranjith XII E 37

Page 1 of 21
 UNITED INDIAN SCHOOL, KUWAIT

BONAFIDE CERTIFICATE

Certified to be the Bonafide work done by Miss Sradha Ranjith of

class XII E in the Biology Laboratory during the year 2024-2025.

Date: ………………………….

PGT in Biotechnology
Mrs. Rebeca Ann Thomas
Submitted for ALL INDIA SENIOR SCHOOL CERTIFICATE PRACTICAL
EXAMINATION held in ………………………………………………… at United
Indian School, Abbasiya, Kuwait.

Date: …………………………… External Examiner

Seal

Page 2 of 21
 ACKNOWLEDGE
MENT
I would like to extend my heartfelt thanks to all those who
have contributed to my chemistry project. First and
foremost, I would like to express my deepest appreciation
to my respected teacher Mrs. Rebeca Ann Thomas, for
her valuable guidance and support throughout the project.
I would also like to extend my gratitude to our respected
principal Radhakrishnan Sir for providing me with all the
facilities that were required.
Finally, I would like to acknowledge the contributions of
all the resources that I have used to complete my project.
Their work was instrumental in providing me with the
necessary knowledge and insights to complete my project
successfully

Page 3 of 21
 INDEX
SL TABLE OF CONTENTS PAG
. E NO
N
O
1 INTRODUCTION 5

2 WHAT IS SEED 6
DISPERSAL?
3 IMPORTANCE OF SEED 7
DISPERSAL
4 TYPES OF SEED 11
DISPERSAL
5 ADAPTATIONS FOR 15
SEED DISPERSAL
6 CASE STUDIES: 16
DETAILED ANALYSIS
7 CONCLUSION 18
9 BIBLIOGRAPHY 19

Page 4 of 21
 INTRODUCTI
ON
Seed dispersal is a crucial process in the life cycle of
plants, allowing them to spread their seeds to new
locations where they can germinate and grow. By
dispersing seeds, plants reduce competition with
their offspring for vital resources such as sunlight,
water, and nutrients. This process also helps plants
colonize new areas, ensures genetic diversity, and
supports the overall health of ecosystems.

In this project, we will explore the different methods

of seed dispersal, including dispersal by wind, water,
animals and self-mechanisms. We will examine how
plants have adapted to these methods and study
detailed case examples for each type. Understanding
seed dispersal is essential in appreciating how
plants survive, spread, and contribute to
biodiversity in nature.

Page 5 of 21
 WHAT IS SEED
DISPERSAL?

Seed dispersal is the process by which seeds are

spread away from the parent plant to different
locations where they can grow into new plants.
This movement can occur through various
natural methods, such as wind, water, animals,
gravity, or self-explosion. Seed dispersal helps
reduce competition between the parent plant
and its offspring for resources like light, water,
and nutrients, and also promotes the spread of
plant species to new areas, contributing to
ecological diversity.

Page 6 of 21
Importance of Seed
Dispersal
Seed dispersal plays a critical role in ensuring plant
survival and diversity. The spread of seeds to
different locations:
 Reduces competition between parent and
offspring plants for sunlight, water, and
nutrients.
 Increases genetic diversity by allowing cross-
pollination between different populations of
plants.
 Promotes species survival in the face of
environmental changes, such as climate
fluctuations or habitat destruction.
 Aids in ecosystem recovery, as dispersed seeds
often help colonize areas affected by
disturbances like fires or floods.
Moreover, seed dispersal is an essential process in
agriculture, where the knowledge of how seeds
spread can help in managing crops and preventing
the spread of invasive species.

Page 7 of 21
1. Reduces Competition
Sunlight: When seeds fall directly beneath the parent plant,
the offspring may struggle to get enough light, as the parent’s
larger structure often overshadows them. Insufficient light
can inhibit photosynthesis, slowing the seedling's growth.
Water and Nutrients: Roots from both the parent and
offspring would compete for water and soil nutrients in the
immediate area. This can lead to limited growth and survival
for the younger plants. By spreading seeds over larger
distances, plants ensure better resource access, increasing the
chances of successful growth.

2. Increases Genetic Diversity

Seed dispersal allows plants to colonize new areas, promoting
cross-pollination and increasing genetic diversity:
Genetic variation: is essential for the survival of a species.
When seeds are dispersed over wide distances, plants from
different populations can mix, allowing for cross-pollination.
This mixing of genes introduces more genetic variability,
which is crucial for the species' adaptability to environmental
stressors like diseases, pests, and changing climates.
Prevents inbreeding: Without seed dispersal, plants may
grow in close proximity to relatives, leading to inbreeding.
Inbreeding results in a limited gene pool, which can make
populations more vulnerable to diseases and environmental
changes. Dispersal reduces the chance of this by enabling
breeding between more distantly related plants.

Page 8 of 21
3. Promotes Species Survival
Colonizing new areas: Seed dispersal allows plants to spread
beyond their immediate surroundings, often into
environments with more favourable conditions. For example,
plants that grow in an area with depleted soil nutrients or
increased competition can survive better by dispersing their
seeds to richer, less competitive environments.
Surviving environmental changes: Environmental changes,
such as shifts in climate or habitat destruction, can render a
plant's current habitat unsuitable. Dispersal ensures that
some seeds might reach areas where conditions are still
favourable, helping maintain the species' presence even if the
original habitat becomes inhospitable.

4. Aids in Ecosystem Recovery

Colonizing disturbed areas: After events such as forest fires,
floods, or land clearing, the land may become barren. Wind,
water, or animals may transport seeds to these areas, where
they germinate and start the process of ecosystem recovery.
These early colonizers, often referred to as "pioneer species,"
help create conditions that allow other species to establish.
Stabilizing soil: Dispersed seeds that germinate in
disturbed areas can help prevent soil erosion by anchoring
the soil with their root systems. In the absence of plants,
soil can be washed away by rain or blown away by wind,
further degrading the environment. By re-establishing plant
life, dispersed seeds protect the land from further damage.

Page 9 of 21
5. Agricultural Importance
Seed dispersal has direct implications for agricultural
practices:
Optimizing crop production: Farmers can use an
understanding of seed dispersal mechanisms to manage
crops more effectively. For example, planting crops at
strategic distances helps minimize competition for water,
nutrients, and sunlight. Additionally, knowledge of seed
dispersal patterns can help in creating better crop rotation
plans, which maintain soil fertility and reduce pest build-
up.
Controlling invasive species: Seed dispersal can also be a
challenge in agriculture when it comes to invasive species.
Invasive plants can spread rapidly and outcompete crops
or native plants for resources. Managing seed dispersal, by
either physically removing invasive species or altering
environmental conditions to make dispersal less effective,
can prevent these plants from taking over. This is
especially important in maintaining the balance of
agricultural ecosystems and ensuring the health of crops.

Page 10 of 21
 Types of Seed
Dispersal
Wind Dispersal (Anemochory)
In wind dispersal, seeds are carried by the wind, allowing
them to travel over long distances. Wind-dispersed seeds are
often lightweight and have specialized structures, such as
wings or fluffy appendages, that help them float through the
air.
Examples:
 Dandelion (Taraxacum officinale): Dandelion seeds
have a parachute-like structure called a pappus that
helps them float on the wind.
 Maple (Acer species): Maple seeds have a winged
structure that allows them to spin and glide through the
air, slowing their descent and enabling wind to carry
them away from the parent tree.
 Pine (Pinus species): Pine seeds are light and may have
thin, wing-like structures that help them disperse
through wind currents.

Page 11 of 21
 Dispersal of Dandelion seed by wind

Water Dispersal (Hydrochory)

Water dispersal occurs when seeds are carried by water,
usually in rivers, lakes, or oceans. Seeds adapted for water
dispersal often have buoyant structures that allow them to
float, protecting the seed during its journey.

Examples:
 Coconut (Cocos nucifera): The coconut has a thick,
fibrous outer husk that helps it float on water, allowing
it to be dispersed across oceans to distant shores.
 Lotus (Nelumbo nucifera): Lotus seeds can float on the
surface of water
and remain viable
for long periods,
allowing them to
spread in
freshwater
environments.

Page 12 of 21
  Mangroves (Rhizophora mangle): Mangrove seeds, or
propagules, fall into the water and float until they find
suitable ground, usually along the coasts, where they
germinate.

Dispersal of
coconut seed by
water

Animal Dispersal (Zoochory)

In animal dispersal, seeds are transported by animals. Some
seeds are eaten by animals and later excreted at a new
location, while others have barbs or hooks that stick to
animals' fur or feathers. The interaction between plants and
animals is mutually beneficial, as plants gain dispersal, and
animals often receive food.
Examples:
 Berries and Birds: Birds eat fleshy fruits, such as berries,
and later excrete the seeds at different locations.
 Burdock (Arctium lappa): Burdock seeds have hooks
that latch onto the fur of animals or human clothing,
allowing them to be transported to new areas.

Page 13 of 21
  Squirrels and Nuts: Squirrels bury seeds like acorns for
future consumption, often forgetting about some of the
buried seeds, which then germinate.

Dispersal of
Berries by birds

Self-Dispersal (Autochory)
Some plants have developed mechanisms to disperse their
seeds on their own, without the help of external agents like
wind, water, or animals. These plants usually rely on
mechanical forces to expel their seeds.
Examples:
 Touch-Me-Not (Mimosa pudica): The seed pods of this
plant burst open when touched, flinging the seeds away
from the parent plant.
 Pea Plant (Pisum sativum): When the pea pods dry out,
they split open suddenly, sending seeds flying in
different directions.
Page 14 of 21
  Violet (Viola): The violet plant’s seed pods explode
when they dry, scattering seeds over a small area
around the plant.

Dry seeds of
violet plant
exploding

Adaptations for Seed

Dispersal
Plants have evolved numerous adaptations to ensure the
successful dispersal of their seeds. These adaptations
help maximize the chances of the seeds reaching a
location where they can germinate and grow.
 Wind Dispersal Adaptations: Seeds are typically
lightweight, have wings (e.g., maple seeds), or
fluffy structures (e.g., dandelion pappus) to
increase their buoyancy in the air.
Page 15 of 21
 Water Dispersal Adaptations: Seeds like coconuts
have thick, fibrous husks that allow them to float
and survive in water for extended periods.
 Animal Dispersal Adaptations: Fleshy fruits (e.g.,
berries) are bright and attractive to animals, while
seeds like burdock have hooks that enable them to
latch onto fur or clothing.
 Self-Dispersal Adaptations: Plants with explosive
seed pods, like touch-me-nots, use sudden
mechanical forces to scatter their seeds far away
from the parent plant.
 Gravity Dispersal Adaptations: Heavy seeds, like
acorns or chestnuts, fall directly to the ground,
where they may roll to a new location or be
moved by animals.

Page 16 of 21
 Case Studies:
Detailed Analysis
Wind-Dispersed Seeds
(Anemochory)
Case Study 1: Dandelion (Taraxacum officinale)
Dandelion seeds are carried by the wind using their parachute-
like pappus. This allows them to float over long distances,
often several kilometres. These lightweight seeds are well-
suited to colonizing open areas and disturbed habitats, making
dandelions common in various environments.
Case Study 2: Maple (Acer species)
Maple trees produce winged seeds, known as samaras, which
spin as they fall, allowing the wind to carry them away from
the parent tree. The seeds are designed to glide through the
air, ensuring they travel far enough to avoid competition with
the parent tree.

Self-Dispersal (Autochory)
Case Study 1: Touch-Me-Not (Mimosa pudica)
Touch-me-not plants have seed pods that burst open when
disturbed, scattering their seeds over a wide area. This self-

Page 17 of 21
dispersal mechanism ensures the seeds are spread away from
the parent plant, reducing competition for resources.

Water-Dispersed Seeds
(Hydrochory)
Case Study 1: Coconut (Cocos nucifera)
Coconuts are designed to float in seawater, allowing them to
be carried across oceans to distant islands or coastal areas.
The fibrous husk of the coconut ensures buoyancy, while the
hard shell protects the seed during long journeys.
Case Study 2: Lotus (Nelumbo nucifera)
Lotus seeds float in freshwater environments, spreading
through rivers and lakes. The seeds have a tough outer coat
that helps them remain viable for extended periods, ensuring
that they germinate when they find a suitable environment.

Animal-Dispersed Seeds
(Zoochory)
Case Study 1: Berries and Birds
Many berry-producing plants rely on birds for seed dispersal.
Birds eat the fruits and excrete the seeds at a new location,
often far from the parent plant. This process helps the plant
colonize new areas while providing birds with a food source.
Case Study 2: Burdock (Arctium lappa)
Page 18 of 21
Burdock seeds have hooks that latch onto the fur of animals or
the clothing of humans. These hooked seeds are then
transported to new locations, where they eventually fall off
and germinate.

Page 19 of 21
 Conclusion
Seed dispersal is a vital process that ensures the
survival and spread of plant species. Different
plants have evolved specific adaptations to
disperse their seeds via wind, water, animals, self-
dispersal, and gravity. These strategies not only
help reduce competition between parent and
offspring but also allow plants to colonize new
areas and contribute to biodiversity. Understanding
these mechanisms is essential for both ecological
conservation and agricultural management.

Page 20 of 21
BIBLIOGRAPH
Y

1. CBSE Biology Textbook for Class 12.

National Council of Educational Research
and Training (NCERT), 2024 Edition.
2. Wikipedia. "Seed Dispersal”
3. Khan Academy. "Seed Dispersal: How
Plants Spread Their Seeds." Khan Academy”

Page 21 of 21