4. The zygote divides and develops into the plant embryo. The embryo is made up of two parts:
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The plumule will become the plant shoot. The radicle will become the plant root.
3. Seed (and fruit) formation 1. The embryo becomes part of the seed. 2. A seed is made up of the embryo, food store and a seed coat.
3. After the formation of the seed, the ovary may develop into a fruit. The fruit surrounds the seed and attracts animals that are looking for food.
4. Seed (and fruit) dispersal
The seeds and fruits of a plant must be carried (dispersed) as far from the parent plant as possible. This means that the young plant will not have to compete with the parent for light, space, water and minerals.
Seed coat
Plumule Embryo Radicle
Seeds and fruits are dispersed in the following ways: zz
Food store
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Animal dispersal: animals eat fleshy fruits and pass the seeds out in their faeces. Some plants produce hooked seeds or fruits that stick to animal fur and are dispersed as the animal moves around. For example, cattle disperse the seeds of the burdock thistle.
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Fig. 7.4.6 A seed
z Fig. 7.4.7
Seeds of burdock
thistles being dispersed by a cow
Wind dispersal: seeds that can be carried by the wind are typically small and light. Other plants have special features to help their seeds carry further. For example, dandelions produce a parachute-type fruit and sycamores produce a winged-type fruit.
z Fig. 7.4.8
Dandelion fruit is
dispersed by the wind
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Water dispersal: plants that live in or near water, such as the water lily, produce seeds that float and are carried downstream by the current. Coconuts are fruits that are dispersed by water.
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Self-dispersal: sometimes called explosive seed dispersal. For example, peas are scattered by exploding pea pods after the fruit dries out. Gorse disperses seeds in a similar way.
