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Investigatory Project on Dispersal of Seeds by Various Agencies

 

Aim: Study of Dispersal of seeds by various agencies.


Introduction:

The process of distribution of seeds to long locations away from their parent is referred as dispersal. It helps the new plants to get more chances of getting water, better soil, nutrients, light and space for a better begin of life. The fruits and seeds shows many adaptations for improved dispersal through different agencies.


The dispersal of seeds and fruits are effected by natural agents such as wind (can be called as anemochory), water (can be called as hydrochory) and animals comprising man (can be called aszoochory). In some plants, they exhibit self dispersal under the explosive mechanism (can be called as autochory). Among these the dispersal through the agency of animals is believed to be  the best and most better method.


Materials and Methods


Seeds and fruits of diverse types, knife, forceps, petridishes, hand lens were collected. The collected fruits were observed carefully, then they were classified according to their mode of dispersal. Fruits of different types were cut open and their features were observed and classified.


Observation and Results


The collected seeds were observed carefully and classified according to their mode of dispersal. Then observed their characters and were recorded in tabular column as given below.

 

No:

Plant

Characteristics of seeds/fruits

Mode of dispersal/ External agency

1

Impatients (Balsam)

Capsular fruit, mature fruits burst open with force when touched and seeds are thrown away.

Autochory/ Explosive mechanism

2

Hopea, Shorea Moringa, Dalbergia, Mahagony, Terminalia

Thin wing like expansions were present in seeds/fruits

Anemochory (dispersal by wind)

3

Sonchus,Tridax Chromalina

Fruit single seeded cypsela with a tuft of hair (pappus) at upper end (parachute mechanism)

Anemochory

4

Calotropis, Bombax, Alstonia

Seeds had outgrowths of hair

Anemochory

5

Amaranthus, Chenopodium

Seed/fruit very light, they had floated on the surface of water

Hydrochory (dispersal by water)

6

Cocos (coconut), Cerebera (odalum)

Spongy mesocarp

Hydrochory

7

Boerhavia, Cleome

Fruits were sticky, they stick to the body of animals

Zoochory (dispersal by animal)

8

Achyranthus, Tribulus, Xanthium

Fruits/seeds had barbs, hooks or spines to get attached with the fur of animals.

Zoochory

9

Lorantus, Viscum

Seeds were sticky. They stuck to the beak of the birds.

Zoochory

10

Ficus

Fruit edible, chiefly eaten by birds, seeds released through faeces.

Zoochory

 

Discussions and Conclusions


In the present study, the dispersal of seeds and fruits were effected by natural agents and animals including man. However some seeds showed autochory.

 

Viva Questions on Study of Dispersal of seeds by various agencies

 

1. What are the external agencies which help in dispersal of seeds?

Wind, water and animal are the external agencies that help in dispersal of seeds.


2.  Why is it necessary for plants to disperse their fruits and seeds to distant places?

Dispersal of seeds and fruits avoid competition and overcrowding of seedlings and also help in the propagation of the species to far away places from the parent place.


3. How do animals help in dispersal of seeds?

Many seeds and fruits are sticky or have spines on their surface to stick to the animals and are carried to distant places. Animals eat fleshy fruits and throw away the seeds at different places. Man may introduce the seeds of economically important plants from one place to another.

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