Types of dispersal

There are a number of modes or ways by which seeds may be dispersed, these include:

1. Wind dispersal
2. Water dispersal
3. Animal dispersal 
4. Mechanical dispersal

Wind Dispersal:

Plants using the wind to disperse their seeds may exhibit the following characteristics:

Very light seeds which the wind can easily carry, as in many grasses like "Fowl foot" grass.	Fowl foot grass (Eleusine indica) has numerous small light seeds
Seeds covered in feathery materials, that act like parachutes when caught in the wind, as in the Oleander.	Oleander seed with 'parachutes'
Seeds that look and act like helicopter rotors, which may spin and fly in the wind, the  Mohogany being a local example.	Closed mohogany pod in tree.	Mohogany pods open on the tree to release seeds.
Parts of a mohogany pod.	Mahogany (Swietenia mahagoni) seeds below spiral through the air like helicopter rotors.

Seeds that flutter or spin in the wind.

Foliage, flower, fruit and seed of the Jacaranda

Water Dispersal:

Plants using water to disperse their seeds may exhibit the following characteristics:

Coconut trees (Cocos nucifera) growing near the sea	A tendency to grow near the sea or rivers	A young manchineel tree (Hippomane mancinella) growing on the beach
Coconuts have hollow centers and have been known to float hundreds of miles across the sea before rooting successfully	Seeds or fruit that can float, allowing them to be carried away from the mother plant by water	Manchineel fruit rot to leave buoyant, woody, star shaped pits that float in water

Animal Dispersal:

Plants using animals to disperse their fruit may exhibit the following characteristics: 

Fleshy edible fruit, where the flesh is consumed and the seed passed out or discarded at another location
Jackfruit fruit in tree	Mammee apples have edible orange flesh and large seed	A cluster of grapefruits

Sticky or clinging fruit or seeds which attached themselves to passing animals, to be dislodged at another location
"Burr grass" (Cenchrus sp.)	Burr grass fruit may cling to clothing or animal fur. The fruit may then fall off or be removed at another location. Seeds from these fruit may then germinate at the new location, thereby spreading the plant around..	Burr grass fruit clinging to clothing.

Mechanical Dispersal:

Mechanical dispersal is sometimes also referred to as self-dispersal.

Plants that use mechanical means to disperse their seeds may exhibit the following characteristics:

Fruit that split or shatter suddenly, throwing their seeds away from the mother plant
Sandbox seed capsule	The Sandbox tree disperses its fruit mechanically	Seed capsule ruptures suddenly and releases flat round seeds
River tamarind (Leucaena leucocephela) seedpods	Mechanical dispersal is common in many legumes (like peas and beans)	Dry legume seedpods split suddenly along their seams to scatter their seeds

Immature (green), mature (brown), and split river tamarind fruit on tree.