How seeds are scattered
You may think that a plant looks sad as its flowers lose their petals and their smell. However, this means that an important stage in the life cycle of the plant is taking place. Its seeds and fruit are forming. Plants get rid of parts of their flowers once they are no longer any use. This is why petals and stamens fall away after pollination.

The plant makes food in its leaves from air, water and sunlight. The food dissolves in water in the leaves and is moved along tubes down the leaf veins and down the leaf stalks. When the food reaches the stem it is carried along more tubes to the base of the flowers. From here, it travels up inside the ovary. Some of the food goes to the ovary wall where the fruit forms. The rest of the food goes to the ovules and is used to change them into seeds.

In time the fruit is fully formed and ready for dispersal. Before the fruit leaves the plant, water is drawn from the seeds to make them lighter and to help them survive in the cold. The lack of water in the seeds makes them less likely to be attacked by moulds. In many plants, water is also drawn from the attachment of the fruit to the stem. This makes the attachment brittle so the fruit can be easily snapped off.

People often get confused about fruits and seeds. A fruit is a part of the plant which helps the seeds to disperse. It is made from the ovary after fertilisation has taken place. A seed is a container which holds a tiny plant and a food store. It is made from the ovule after fertilisation has taken place.

In the autumn, many people become aware of the dispersal of fruits. They see winged fruits from sycamore and maple trees spinning down through the branches. They also see white clouds of willow-herb seeds drifting across waste ground and into parks and gardens. At the same time they may see the bright red berries of the mountain ash and the hawthorn. These fruits are using a different method to scatter their seeds. They are attracting animals to eat them. This may seem surprising because when animals eat food they break it up, in a process called digestion. However, the seeds in the berries can cope with that. They have particularly tough coats which let them travel all the way through the animal's digestive system unharmed. It takes some time for an animal, such as a bird or mammal, to digest its food, so the chances are, that when the seed leaves the animal, it may be many kilometres away from its parent. While many plants are letting the wind or animals carry away their seeds, some plants, such as the balsam, shoot their seeds into the air. These plants have fruits called pods. When the seeds are ready to be dispersed, the plant draws water from the walls of the pod and dries them out. As the walls dry, they twist. This makes parts of the wall pull on other parts. The strength of the pulls suddenly makes the walls break open. As they do so, they fling out the seeds.

It may seem that plants go to a great deal of trouble to disperse their seeds. The trouble is very well worth it. If the seeds were just to fall among the parent's roots, the seedlings would be so crowded that few would grow and breed. By spreading out, the seeds stand a better chance of completing their life cycles and helping their kind survive.

Are all fruits juicy?
No. We tend to think of fruits as juicy because we eat oranges and apples but in fact some fruits are dry. Some dry fruits split open when they are ripe. The pea pod is an example of this. Another example is the fruit of the horse chestnut in which you find a seed called a conker. Some dry fruits do not split up. Nuts such as the hazel and the acorn are examples of dry fruits. Grass seeds and cereal grains are really dry fruits too.

Why are some berries poisonous?
They may be poisonous to us but some animals do not find them poisonous and can eat them. You should not eat any berries in the countryside unless allowed to do so by a responsible adult.

Why do some fruits have a spiky coat?
They have spikes to grip onto the hairs and feathers of passing animals. The fruits can travel for many kilometres before the animal brushes them off. The goose grass is a common example of a plant which has spiky fruits. You can find it growing low down in a hedge. Small mammals, such as mice, move through the lower part of the hedge and sometimes carry away the fruits.

Can animals transport seeds in other ways on the outside of their bodies?
Yes. Some fruits such as the mistletoe are very sticky. When a bird has finished feeding on them some of the seeds stick to the beak and are carried away. Animals can pick up seeds on the ground with their feet and carry them away.

How do parachutes and wings of seeds help to disperse them?
The parachutes and wings offer resistance to the air. This means that when the seeds fall, they fall more slowly. By increasing the time spent falling, they also increase the chance of a wind blowing them along. The parachute or wing can also catch the wind and be pushed along by it.

In cowboy films or westerns you sometimes see whole plants blowing along. Are they dispersing seeds?
Yes, they are. The plants are tumbleweeds and pigweeds. When the seeds are ready to disperse the whole shoot dries out and snaps off from the root. It is then blown about the desert, or through a town, dispersing its seeds.

Why do plants produce so many fruits and seeds?
When fruits are dispersed, most of them do not land in places where the seeds can germinate and produce new plants. The seeds in the fruit simply die. If only a small number of fruits are produced there is a good chance that none of them will find suitable conditions and all the seeds will die. If a large number of fruits and seeds are produced there is a better chance that some seeds will find a suitable place to germinate and grow into a plant.

If you touch a puff ball fungus a cloud of brown specks come out. Are they seeds or pollen?
They are neither. They are spores. Fungi such as the puffball and the mushroom do not make pollen or seeds because they are not plants. Inside the spore is a piece of the fungus.

If it lands in a suitable place it will grow. Fungi use two methods of dispersal that plants use. They produce a large number of the parts they are dispersing (the spores in fungi, the seeds in plants) and they use the wind as a means of dispersal.