Some fruits mechanically eject fruits, some at a violent velocity. Humans are another method of dispersal whether intentionally or not. Most countries have regulations with regards to bringing fruits and seeds into the country that may harm native species and cultivated crops.
Category: 4. Fruit and Seed Dispersal
Dispersal by water
Some fruits contain trapped air and are thus adapted to dispersal by water. Some pericarps are thick and spongy enough to absorb water slowly and will thus protect the tiny embryo held within. Saltwater dispersed plants generally have these type pericarps and survival requires washing up on a beach somewhere before the saltwater reaches the inside of the seed.
Dispersal by animals
There are so many adaptations for the dispersal of seeds by animals that it would take a volume or two to discuss them all. Birds can carry seeds in the mud that they pick up on their feet. Seeds pass through digestive tracts and are deposited randomly by animals. Ants carry collect and carry seeds. Some seeds will not germinate unless they have passed through the acidic environment of a digestive tract. Fur and feathers can trap seeds and some seeds have burrowing type screws or hooks to ensure getting caught on something and carried along.
There are a variety of methods that will get seeds from the ovary to a fertile spot to begin germinating and growing. Not all methods will work for every plant and some plants are very method specific.
Dispersal by wind
The wind can carry light seeds for miles and most seeds and fruits relying on wind dispersal have specialized adaptations. The samaras with their wings and membranes are highly ideal fruits for wind dispersal. Some fruits are too large to be carried in the air but can be rolled along by the wind. Cottony or woolly hair type adaptations as in the Willow Family, enable the better transfer of seeds via the wind. Tumbleweed plants break off and blow along in the wind, all the while dispersing seeds as it bumps along.