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DAV PUBLIC SCHOOL, JA, DERA

Submitted in the partial fulfillment of the requirement

for the AISSCE CBSE Board Examination

In
BIOLOGY

For the Academic year

2023-24 To

be carried out by:

Name: Amrit Mohanty

Roll - 22
Under The guidance :
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DAV PUBLIC SCHOOL

MCL,JA,DERA

Department of Biology

Certified that the project work entitled “Study of Dispersal of Seeds

by Various Agencies” carried out by Amrit Mohanty Roll No:02 , of
class XI ‘B’ is a bonafide work in partial fulfilment of AISSCE in the
subject of biology prescribed by the Central Board of Secondary
Education, during the year 2023-2024. It is certified that all
corrections/suggestions indicated for Internal Assessment have been
incorporated in the Report deposited in the departmental library.
The project report has been approved as it satisfies the academic
requirements in respect of the Project work prescribed for the said
examination.

Name & Signature of the Student

Name & Signature of the Guide Signature of the

Principal

Name of examier and Signature with Date

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Through this acknowledgement we express our

sincere gratitude to all those people who have

been associated with the project and have helped
us with it and made it a worthwhile experience.
We extend our thanks to Smt. Shukla Chakraborty,
the principal of this fine establishment DAVPS
MCL,DERA for being pillar of support throughout
the process. We would like to express our
gratitude towards our parents our parents for
their cooperations and encouragement which
helped us in the completion of this project. We
would also like to express our thanks to Mrs.
Ashabari Sahoo, the head of biology department of
DAVPS MCL, DERA who gave us this opportunity to
learn the subject with a practical approach, guided
us and gave us valuable suggestions regarding the
project.

S. No. Content Page No.

1 Certificate 2
2 Acknowledgment 3
3 Introduction 5
4 Theory 6
5 Types of Seed 7
Dispersal(Autochory)
6 Dispersal by 8
wind(Allochory)
7 Dispersal by 9
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water(Hydrochory)
8 Dispersal by 10
animals(Zoochory)
9 Dispersal by 11
humans(Athropochory)
10 Experiment 12
11 Observation Table 13&14
12 Conclusion & 15
Bibilogrpahy
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The process of scattering of fruits and seeds to distant places away

from their parent is called dispersal or dissemination. It provides the
new plants better chances of obtaining water, nutrients, light and
space thereby enabling them to have a better start in life.

The fruits and seeds develop many devices for better dispersal
through different agencies.

The principal agencies that aid in the dispersal of fruits and seeds are
wind(anemochory), water(hydrochory) and animals including
man(zoochory). Besides, some plants show self dispersal by explosive
mechanism(autochory). The dispersal through the agency of animals
is considered as the best and most successful method. Dispersal of
seeds and fruits is quite interesting subject of natural phenomenon
and hence the study of dispersal of seeds by various agencies has
been selected for the present project.
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BENEFITS OF SEED DISPERSAL:

Seed dispersal is likely to have several benefits for different plant

species.
1. Seed survival is often higher away from the parent plant. This
higher survival may result from the actions of density-dependent
seed and seedling predators and pathogens, which often target the
high concentrations of seeds beneath adults.Competition with
adult plants may also be lower when seeds are transported away
from their parent.

Seed dispersal also allows plants to reach specific habitats that are
favorable for survival, a hypothesis known as directed
dispersal.Male bellbirds perch on dead trees in order to attract
mates, and often defecate seeds beneath these perches where the
seeds have a high chance of survival because of high light
conditions and escape from fungal pathogens.

2. In the case of fleshy-fruited plants, seed-dispersal in animal

guts (endozoochory) often enhances the amount, the speed, and
the asynchrony of germination, which can have important plant
benefits.

3. Seeds dispersed by ants (myrmecochory) are not only

dispersed short distances but are also buried underground by the
ants. These seeds can thus avoid adverse environmental effects
such as fire or drought, reach nutrient-rich microsites and survive
longer than other seeds.

4. These features are peculiar to myrmecochory, which may

thus provide additional benefits not present in other dispersal
modes.

5. Finally at another scale, seed dispersal may allow plants to

colonize vacant habitats and even new geographic regins.
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Autochory
1. Barochory or the plant use of gravity for dispersal is a simple
means of achieving seed dispersal. The effect of gravity on heavier
fruits causes them to fall from the plant when ripe. Fruits
exhibiting this type of dispersal include apples, coconuts and
passion fruit and those with harder shells (which often roll away
from the plant to gain more distance).Gravity dispersal also allows
for later transmission by water or animal.

2. Two other types of autochory not described in detail here are

blastochory, where the stem of the plant crawls along the ground
to deposit its seed far from the base of the plant; and herpochory,
where the seed crawls by means of trichomes or hygroscopic
appendages (awns) and changes in humidity.

By Wind(Allochory )

1.
Wind dispersal (anemochory) is one of the more primitive
means of dispersal. Wind dispersal can take on one of two primary
forms: seeds or fruits can float on the breeze or, alternatively, they
can flutter to the ground.

2.
The classic examples of these dispersal mechanisms, in the
temperate northern hemisphere, include dandelions, which have a
feathery pappus attached to their fruits (achenes) and can be
dispersed long distances, and maples, which have winged fruits
(samaras) that flutter to the ground.
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3. An important constraint on wind dispersal is the need for

abundant seed production to maximize the likelihood of a seed
landing in a site suitable for germination. However, limited wind in
its habitat prevents the seeds to successfully disperse away from
its parents, resulting in clusters of population.

Reliance on wind dispersal is common among many weedy or

ruderal species.

By Water(Hydrochory)

Many aquatic (water dwelling) and some terrestrial (land

dwelling) species use hydrochory, or seed dispersal
through water. Seeds can travel for extremely long
distances, depending on the specific mode of water
dispersal; this especially applies to fruits which are
waterproof and float on water.

The water lily is an example of such a plant. Water lilies'

flowers make a fruit that floats in the water for a while
and then drops down to the bottom to take root on the
floor of the pond.
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The seeds of palm trees can also be dispersed by water. If

they grow near oceans, the seeds can be transported by
ocean currents over long distances, allowing the seeds to
be dispersed as far as other continents.

By animals(zoochory)

Animals can disperse plant seeds in several ways, all

named zoochory. Seeds can be transported on the outside
of vertebrate animals (mostly mammals), a process
known as epizoochory. Plant species transported
externally by animals can have a variety of adaptations
for dispersal, including adhesive mucus, and a variety of
hooks, spines and barbs.

However, epizoochory is a relatively rare dispersal

syndrome for plants as a whole; the percentage of plant
species with seeds adapted for transport on the outside of
animals is estimated to be below 5%.
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Seed dispersal via ingestion and defecation by vertebrate

animals (mostly birds and mammals), or endozoochory, is
the dispersal mechanism for most tree
species.Endozoochory is generally a coevolved mutualistic
relationship in which a plant surrounds seeds with an
edible, nutritious fruit as a good food resource for animals
that consume it.Birds and mammals are the most
important seed dispersers, but a wide variety of other
animals, including turtles, fish, and insects can transport
viable seeds.

Seed predators, which include many rodents (such as

squirrels) and some birds (such as jays) may also disperse
seeds by hoarding the seeds in hidden caches.The seeds
in caches are usually well-protected from other seed
predators and if left uneaten will grow into new plants.

In addition, rodents may also disperse seeds via seed

spitting due to the presence of secondary metabolites in
ripe fruits.

Other types of zoochory are chiropterochory (by bats),

malacochory (by molluscs, mainly terrestrial snails),
ornithochory (by birds) and saurochory (by non-bird
sauropsids).

By humans (Anthropochory)

Dispersal by humans (anthropochory) used to be seen as

a form of dispersal by animals.Recent research points out
that human dispersers differ from animal dispersers by
having a much higher mobility, based on the technical
means of human transport. On the one hand, dispersal by
humans also acts on smaller, regional scales and drives
the dynamics of existing biological populations. On the
other hand, dispersal by humans may act on large
geographical scales and lead to the spread of invasive
species.Humans may disperse seeds by many various
means and some surprisingly high distances have been
repeatedly measured.Examples are: dispersal on human
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clothes (up to 250 m),on shoes (up to 5 km),or by cars

(regularly ~ 250 m, singles cases > 100 km).

Aim of the experiment: To study the dispersal of seeds by various

agencies.

Materials Required: Different types of seeds and fruits, knife,

forceps, petridishes, hand lens etc.

Experimental Procedure
1. Collect different types of seeds and observe their features carefully,
classify them according to their mode of dispersal.
2. Similarly cut open different types of fruits, note down the features of
their seeds and classify them according to their mode of dispersal.
3. Record your observation in the form of a table given as follows.
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S. No. Plant Characteristics Mode of

of seeds/fruits dispersal/External
agency
1 Impatiens(Balsam) Capsular fruit, Autochory/Explosive
mature fruit burst mechanism.
open with force
when touched and
seeds are short
several feet away.
2 Viola(Pansy) Fruit capsule, Autochory/Explosive
tension develops in mechanism.
the drying wall of
the carpels causing
the fruit to burst
open along the line
of dehiscene.
3 Acer(Maple), Thin, wing like Anemochory/Dispersal
Hopea, Tecoma, expansions are by wind.
present in
Haloptelia(Chilbil), seeds/fruits, Wings
Shorea(Sal), Elm, provide large
Moringa, surface area to the
Jacaronida, wind for their
dispersal.
Cinchoria,
Albizia(Siris),
Dalbergia(Shisham
) etc.
4 Dandilion, Fruit single seeded Anemochory/Dispersal
Sonchus. cypsela with a tuft by wind.
of hair(pappus) at
upper end. Pappus
open out like a
parachute.
5 Calotropis (Ak), Seeds have Anemochory/Dispersal
Alstonia, Bombax hairy outgrowth by wind.
(Sembal) to provide large
surface area to
the wind.
6 Chenopodium Seed/fruit very Hydrochory/Dispersal
(Bathua), light, float on by water.
Polygonum the surface of
water.
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7 Nymphea (Water Spongy Hydrochory/Dispersal
lily) Nelumbium thalamus or by water.
(Lotus) Cocus spongy

(Coconut) mesocarp of the

fruit.
8 Boerhaavia, Fruits are sticky Zoochory/Dispersal by
Plumbago, Cleome and can stick to the animals.
body of animals.
9 Achyranthus Fruits/Seeds have Zoochory/Dispersal by
(Phuthkanda), barbs, hooks, or animals.
spines to get attach
Xanthium, with the fur of
Tribulus, animals.
Medicago(Maina),
Martynia (Tiger’s
claw)
10 Loranthus, Viscum, Seeds are sticky, Zoochory/Dispersal by
Cordia (Lasoora) seed stick to the birds.
beak of the birds.
11 Ficus (Banyan and Fruits edible, Zoochory/Dispersal by
Pipal tree) chiefly eaten by birds.
birds, seeds
released unharmed
with faeces.
12 Crop plants Fruits/Seeds have Zoochory/Dispersal by
(Cereals, pulses, economic man.
importance.
spices etc.)
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CONCLUSION

Seed dispersal has many consequences for the ecology

and evolution of plants.Dispersal is necessary for species
migrations, and in recent times dispersal ability is an
important factor in whether or not a species transported to
a new habitat by humans will become an invasive species.
Dispersal is also predicted to play a major role in the origin
and maintenance of species diversity. Seed dispersal is
essential in allowing forest migration of flowering plants.

In addition, the speed and direction of wind are highly

influential in the dispersal process and in turn the
deposition patterns of floating seeds in the stagnant
water bodies. The transportation of seeds is led by the
wind direction. This effects colonization situated on the
banks of a river or to wetlands adjacent to streams
relative to the distinct wind directions. The wind dispersal
process can also affect connections between water
bodies.

BIBILOGRAPHY

1.Guidance from the Teacher

2.Comprehensive Biology Practical Book
3.www.google.com
4.Wikipedia
5.ChatGPT
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