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 Seed Dispersal

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Matías Christiansen
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Macarena Moreno




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Join date : 2010-08-05

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PostSubject: sunflower seed dispersal   Seed Dispersal - Page 2 Icon_minitimeSun Oct 17, 2010 7:49 pm

Dispersal is necessary for plant because that is the only way the younger plants can survive for a longer time. There are several ways of dispersion:
1. Wind: When wind blows hard enough it catches the seeds and blow them away until they find a new location. Example: dandelion, sycamore
2. Animals: When an animal eats a fruit, the seed is not digested so is expelled away by the animal faces. Example: plum
3. Water: waterproof fruits travel by water until they find their new location. Example: Coconut
4. Catching a lift: Some seeds have tiny hooks that attaches to the animal fur or clothes and carried away until they fall out. Example: aven
5. Explosive mechanism: some trees have casings that split and twist, throwing the seeds away. Example: lupin

SUNFLOWER SEED
The sunflower have enormous amount of seeds. This seeds are dispersed by wind, animal, catching a lift and water
1. Wind: the sunflower seed have a structure similar to a parachute. It is composed by a papus (the parachute), the stem and the seed, which is found at the end of the stem. When the wind blows, it catches the papus with the seed and throws it away.
2. Animal: the “large sunflower” is a bigger type of sunflower that does not produce a papus. The way it is dispersed is by the birds, which the catch the seed and throw them away.
3. Catching a lift: the “notorious cocklebur” produces a type of hook that attaches to the animal fur and carried away until they fall.
4. Water: sometimes the seeds land in water. They are carried away until they find their new location. This is considered the less effective way of dispersion.

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Emilia Valenzuela




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Join date : 2010-08-05

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PostSubject: Re: Seed Dispersal   Seed Dispersal - Page 2 Icon_minitimeSun Oct 17, 2010 8:08 pm

Seed dispersal is the movement and the transport of seeds away from the parent plant. Seeds can be dispersed by wind, animals and also by water.

Sunflower (Helianthus annuus)

Its made by many small flowers crowded together. The outer flowers (ray florets) are often yellow, brown and orange. The flowers inside the circular head (disc florets) mature into seeds.

Wind: When the flower goes to seed, they form structures similar to parachutes. The top part of the tiny parachute is called the pappus, has hair and its very light. The stem attaches to the pappus and the bottom of the seed or fruit of the sunflower. Wind catches the hairy part of the pappus and lifts the seed from the plant into the air. When the wind is strong enough it can carry the pappus for miles, but when it’s to weak, the pappus comes to rest and attaches in a new location.

Animals: some types of sunflowers do not have pappus so animals also may help on the transport. The big seed are the favourite of birds for example, they carry them away or cause them to fall. Some seeds can get caught into the animals fur.

Water: some seeds might get into rivers and streams for example. The water carries the seed downstream until it becomes settled or picked up again by another animal. This is the less efficient form of dispersion according to the sunflower

Seed Dispersal - Page 2 Sunflo10

PD: sorry, I just realized (after I posted in the forum) I did the same flower as Macarena Moreno, but I didn't notice page 2 existed before I post this, and we posted on the forum nearly the same time.


Last edited by Emilia Valenzuela on Sun Oct 17, 2010 8:19 pm; edited 1 time in total (Reason for editing : confusion)
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jpsuazo




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Join date : 2010-08-05

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PostSubject: Re: Seed Dispersal   Seed Dispersal - Page 2 Icon_minitimeThu Oct 28, 2010 6:38 pm

Leguminosae: explisive seed dispersal.

Seed dispersal is very important for the reproduction of plants first because if the seed falls too near to the mother plant, the mother plant will take all the nutrients from the ground and will not let the near plant to grow. Also if the plant manages to grow and pollinates his mother plant, there will be no variation in the genetic material.

Explosive seed dispersal is the kind of dispersal when the fruit bursts open by elastic contraction in tissue. The fruits of leguminosae is shaped in order to burst open through two “weak points” so when the fruit bursts open, the seeds will go further away from the mother plant as possible.

The mayor advantage of this method is that the seeds go in different directions when the fruit bursts, contrary to animal and wind dispersal when all the seeds go the same direction.

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PostSubject: Re: Seed Dispersal   Seed Dispersal - Page 2 Icon_minitime

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