A seed is far more than a small package of plant material. It protects and feeds the next generation, lets a plant survive harsh conditions, and helps the species spread to new places. These features make seeds central to the survival of flowering plants.
Protection and food
The tough seed coat (testa) shields the embryo from drying out, from physical damage and from many pests and diseases. The food store in the endosperm or cotyledons nourishes the embryo during germination, before the young plant can make its own food by photosynthesis.
Dormancy
Dormancy is a resting state in which the seed has a very low metabolic rate and does not germinate, even in moist conditions, until it is favourable to grow. Dormancy lets seeds:
- survive drought, cold or fire until conditions improve;
- germinate at the right time of year, so seedlings are not killed by an unsuitable season;
- be stored and transported without dying.
Seed dispersal
Dispersal is the scattering of seeds away from the parent plant. It reduces competition for light, water and minerals between the parent and its offspring and among the offspring, and lets the species colonise new areas.
| Agent | Adaptation | Example |
|---|---|---|
| wind | light, winged or hairy seeds | Angsana, dandelion |
| water | buoyant, waterproof fruit | coconut |
| animals | hooks, or fleshy fruit that is eaten | Love grass, guava |
| self (explosive) | pod splits and flings seeds | balsam, Hura |
Key idea
Seeds aid survival in three ways: protection and food for the embryo, dormancy to wait out bad conditions, and dispersal to reduce competition and colonise new areas.
Example
A coconut has a light, fibrous, waterproof husk that lets it float across the sea and germinate on a distant beach — an adaptation for dispersal by water.
Remember
Protection (testa) + food (endosperm/cotyledons) + dormancy + dispersal = survival and spread of the species.