They have a protective coat which allows them to survive harsh conditions.
What are seeds for?
They grow into new plants and so keep the species going.
Their design often helps them to be spread away from the parent plant, e.g. by wind (fluffy thistle seeds), by water (buoyant coconut and flax seeds) and by animals (edible acorns, walnuts and berries). This process is called dispersal.
What is needed for germination?
Seeds need all three of the following to germinate: oxygen, water and warmth.
Some seeds have special dormancy which must be ‘broken’ before germination can begin, e.g. acorns need to be chilled for several weeks and gorse seeds need heat (for example from a fire).
What is needed by plants for continued growth?
Plants need carbon dioxide, water and sunlight for growth (all are used in photosynthesis). Oxygen is a waste product of photosynthesis.
They need nutrients like nitrogen, phosphorus and potassium to grow.
They need soil or some other medium to anchor themselves, allowing them to stand upright.
Why do we need plants?
For food and fibres.
To feed animals.
To produce oxygen.
To bind soil and so reducing erosion.
To soak up excess water during high rainfall and so reducing flooding.