Seed dispersal

Plants cannot walk to new homes. Instead, they move their seeds.

Some seeds use the wind to fly.

Others fall down using gravity.

Some seeds use animals to travel. Small hooks help seeds stick to fur.

Other seeds are inside tasty fruit. Birds eat the fruit and drop the seeds later.

Seeds can also float on water. This helps them reach far lands. Moving seeds helps new plants grow well. They find better spots to live.

Plants cannot walk to new places. Instead, they move their seeds away from the parent plant. This is called seed dispersal. Moving seeds helps new plants find better spots to grow. It also helps them avoid pests that live near the parent plant.

Some plants move seeds using their own power. This is called autochory. One way is ballochory. This is when a fruit explodes to throw seeds out. The dynamite tree uses this way. It can throw seeds up to 100 meters!

Other plants use outside help. This is called allochory. Wind can carry seeds. Dandelions use feathery parts to float on the breeze.

Water can also move seeds. Some seeds float to reach new lands.

Animals help move seeds too. Some seeds have hooks to stick to fur. This is called epizoochory.

Other animals eat fleshy fruit. The seeds then move through their guts.

This helps seeds grow in new places.

Plants cannot move from place to place like animals do. Instead, they use seed dispersal to spread their offspring. This is the movement of seeds away from the parent plant. Dispersal is very important for a plant's survival. It helps seeds find new habitats where they can grow well. It also helps them avoid competition with the parent plant. Moving away from the parent also keeps seeds safe from pests and diseases.

There are many ways this happens. Some plants use their own power, which is called autochory. One way is ballochory, where a fruit explodes to throw seeds out. This can happen because of pressure inside the fruit. The Hura crepitans is a famous example. People call it the dynamite tree because its fruit explodes so loudly. It can throw its seeds up to 100 meters away!

Another way is gravity, or barochory. This is when heavy fruits like coconuts or apples simply fall down.

Other plants use outside help, which is called allochory. Wind is a common helper, known as anemochory. Some seeds have feathery parts to float on the breeze. Dandelions are a great example of this. Other seeds, like maple seeds, have wings to help them flutter.

Water can also move seeds through hydrochory. Many aquatic plants use this way to travel. Some seeds are waterproof so they can float for a long time. Palm seeds can even travel on ocean currents to new continents.

Animals are also very important for moving seeds. This is called zoochory. Some seeds use epizoochory, which means they stick to the outside of an animal. They might have hooks, spines, or sticky mucus to grab onto fur. A clover plant uses stiff hairs to stick to animals.

Other seeds use endozoochory. This happens when an animal eats fleshy fruit. The seeds then travel through the animal's gut and come out in droppings.

Sometimes, seeds move in very long distances. This is called long-distance dispersal. One way is to use two different methods one after another. This is called diplochory. It is like a relay race for seeds. Some seeds might even travel in very unusual ways. One example involves seeds being carried by a shark's egg case. This helps plants colonize new and empty lands. By spreading out, plants can find the best spots to thrive.

Seed dispersal is the movement of seeds away from a parent plant. Since plants have limited mobility, they must rely on various methods to spread their offspring. This process is vital for the survival and growth of plant populations. Dispersal helps plants reach favorable habitats and colonize new geographic regions. It also reduces competition with the adult plant for resources like light and water. Furthermore, moving away from the parent helps seeds avoid high concentrations of predators and pathogens.

Scientists divide seed dispersal into two main categories: autochory and allochory. Autochory occurs when a plant uses its own internal mechanisms to move its seeds. This method usually limits how far the seeds can travel. Allochory occurs when an external agent, known as a vector, transports the seeds. These vectors can be non-living, such as wind or water, or living, such as animals. Many plants actually use more than one dispersal phase to move their seeds. This sequential process is known as diplochory.

Autochory includes several distinct methods. One type is barochory, which uses gravity to disperse seeds. Heavier fruits, like coconuts or apples, simply fall from the plant when they are ripe. Another type is ballochory, or explosive dehiscence. In this process, seeds are forcefully ejected by internal pressure or tension. The Hura crepitans, often called the dynamite tree, is a famous example. Its fruit explosions are powerful enough to throw seeds up to 100 meters. Other plants, like witch hazel, use a non-explosive version of ballochory to squeeze seeds out at 45 km/h.

Wind dispersal, or anemochory, is one of the most primitive dispersal modes. Seeds may float on the breeze or flutter toward the ground. Dandelions use a feathery structure called a pappus to travel long distances. Maple trees use winged fruits called samaras to help them flutter down. Some plants, like tumbleweeds, move by letting the entire plant blow in the wind. However, wind dispersal requires the production of many seeds to ensure some land in good spots. Some species, like those in the Asteraceae family on islands, may evolve smaller dispersal capabilities over time.

Hydrochory is the process of dispersal through water. This is common for both aquatic and land-dwelling species. Many seeds are waterproof and can float for extremely long periods. For example, water lily seeds float before sinking to take root on the pond floor. Palm tree seeds can use ocean currents to travel between different continents. Mangrove trees also rely on water, as their seeds can be carried away by high tides. These seeds are ready to grow as soon as they touch soil.

Animals contribute to dispersal through a process called zoochory. This can happen via epizoochory, where seeds attach to the outside of an animal. Plants often develop hooks, spines, or sticky mucus to facilitate this. An example is the clover, which uses stiff hairs to cling to animal fur. It is estimated that fewer than 5% of plant species use this specific method. Another way is endozoochory, where animals eat fleshy fruits. The seeds then pass through the animal's gut and are deposited in droppings. This can increase the speed and success of germination.

Long-distance dispersal (LDD) is a special category of spatial dispersal. It is measured in two ways: proportional distance and actual distance. Proportional distance looks at the percentage of seeds that travel the farthest. Actual distance uses a specific threshold, such as 1 kilometer, to define LDD. There is also a non-standard form of LDD that involves unpredictable events. For instance, a tree seed might travel to a different continent by sticking to a shark's egg case. These extreme dispersal events are essential for plant fitness and migration.