What is a seed?
Seeds come in all shapes, sizes and colours depending on the type of plant. Seeds contain the embryo (the baby plant) and food for the embryo. The outside of the seed has a protective coat to keep the embryo safe inside. Seed coats can be very hard or soft.
What is seed dispersal?
Seed dispersal is how seeds spread or scatter from the parent plant to a new place. If the seeds land too close to the parent plant they will compete with it for water, sunlight and soil.
Plants that only live for one season simply let their seeds fall to the ground nearby. They know they won’t live for long and won’t have to compete with their babies.
How are seeds carried away?
Wind dispersal - Seeds are carried away by the wind. These seeds are very light and can have hairs or wings to help them float in the air, like dandelion seeds that fly like tiny parachutes.
Seeds carried by the wind can travel very far but they don’t always land in a good place to grow! This is why plants that rely on the wind produce many seeds.
Animal dispersal - Seeds can either stick to animal fur or feathers or they can be eaten. The seeds get taken from place to place in the animal's droppings. Another form of animal dispersal is when squirrels bury nuts in the ground. Some of the buried nuts get forgotten about and start to grow into trees.
Water dispersal - Seeds get carried away by rivers, streams, oceans or floods. For example, the seeds of palm trees, called coconuts, are carried to different places by the ocean.
What is germination?
Germination is when a seed starts to grow. Seeds do not germinate until they are ready. Until then, they can stay in a dormant (sleep-like) state.
When a seed is ready to germinate, the plant inside starts to grow until it pushes open the seed coat, similar to a chick hatching from an egg.
The germination stage is over as soon as the plant pops out from the soil.
What do seeds need to germinate?
Some seeds need light to germinate, others need darkness. All seeds need:
1. Oxygen
2. Water
3. The right temperature
Did you know?
- Plants that do not make seeds, like ferns and mosses, make spores which germinate instead of seeds. Spores cannot live as long as seeds.
- Poppy seeds are contained inside pods that are like salt and pepper shakers. When the winds blow, the pods get shaken and let out seeds.
