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Page 6

Theory

Benefits

Seed dispersal is likely to have several benefits for 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 regions.

Gravity (Autochory)

1.Barochory or the plant use of gravity for dispersal is a

https://en.wikipedia.org/wiki/Seed_predation
https://en.wikipedia.org/wiki/Myrmecochory
https://en.wikipedia.org/wiki/Competition_(biology)
https://en.wikipedia.org/wiki/Pathogens
https://en.wikipedia.org/wiki/File:Entada_phaseoloides_MHNT_graines.jpg

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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, coconutsand passionfruit 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 are ballochory (the seed is forcefully ejected by
dehiscence and squeezing) and herpochory(the seed crawls by means of trichomes and
changes in humidity).

Wind Allochory

* Wind dispersal of dandelion seeds Entada phaseoloides – Hydrochory Wind dispersal
(anemochory) is one of the more primitive means of dispersal. Wind dispersal can take
on one of two primary forms: seeds can float on the breeze or alternatively, they can
flutter to the ground.
* The classic examples of these dispersal mechanisms
include dandelions, which have a feathery pappus
attached to their seeds and can be dispersed long
distances, and maples, which have winged seeds
(samara) and flutter to the ground. An important
constraint on wind dispersal is the need for abundant
seed production to maximise 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.

https://en.wikipedia.org/wiki/Ruderal
https://en.wikipedia.org/wiki/Weed
https://en.wikipedia.org/wiki/Germination
https://en.wikipedia.org/wiki/Samara_(fruit)
https://en.wikipedia.org/wiki/Maple
https://en.wikipedia.org/wiki/Pappus_(flower_structure)
https://en.wikipedia.org/wiki/Dandelions
https://en.wikipedia.org/wiki/Dandelion
https://en.wikipedia.org/wiki/Trichome
https://en.wikipedia.org/wiki/Dehiscence_(botany)
https://en.wikipedia.org/wiki/Passionfruit
https://en.wikipedia.org/wiki/Coconut
https://en.wikipedia.org/wiki/Apple
https://en.wikipedia.org/wiki/Gravity
https://en.wikipedia.org/wiki/File:Photos-photos_1088103921_Floating.jpg

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8. Boerhavia,Plumbago,Cleo
me.

Fruits are sticky and can stick
to the body of animals.

Zoochory/Dispersal by
animals

9. Achyranthus
(Phuthkanda), Xanthium,
Tribulus, Madicago
(Maina).Martynia
(Tigers Claw)

Fruits and seeds have
barbs,hooks,or spines to get
attach with fur of the animal.

Zoochory/Dispersal by
animals

10 Loranthus, Viscus,
Cordia

Seeds are sticky and seeds
stick to the beek of the
Birds.

Zoochory/Dispersal by
Birds

11. Ficus (Banyan & Pipal
Tree)

Fruits edible, chiefly eaten by
birds,seeds released
unharmed with faeces.

Zoochory/Dispersal by
Birds

12. Crop
Plants(Cereals,pulses,
spices)

Fruits/Seeds have econimic
Importance.

Zoochory/Dispersal by
Man

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.

Dispersal of seeds away from the parent organism has a central role in two major
theories for how biodiversity is maintained in natural ecosystems..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 effect connections
between water bodies. Essentially, wind plays a larger role in the dispersal of

https://en.wikipedia.org/wiki/Forest_migration

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