Hitching a Ride Hitching a Ride Did you ever find little pieces of plants, called burs, stuck to your shoes or pants after a walk through a field? Burs are actually the seedcontaining fruits of some plants. They are covered with prickly little hooks that can “stick” to animals (like you!) that brush against them. That way the burs get a ride to wherever the animal is going. When the bur falls off, the seeds inside are released and a new plant gets a chance to grow. Each fruit has many tiny hooks Common burdock Washed Away Washed Away The lotus plant uses water to spread its seeds! This makes sense because the plant actually grows in water. Its roots are attached to the mud at the bottom of a pond or river but a long stem carries its leaves and flowers to the surface. The fruit of a lotus plant is a flat-topped pod with holes that hold seeds. When the seeds are ripe, the pod tips down and the seeds fall into the water and float away! Lotus seed heads Dried lotus seed head from above Seed held in cup Off to a Flying Start Off to a Flying Start Cow vetch Believe it or not, some plants actually throw their own seeds into the air. How? It’s kind of like what happens when a balloon is filled with too much air. The pressure builds. Finally the balloon explodes and the air rushes out. Some plants, like the Himalayan balsam flower and the cow vetch, grow their seeds in cases. As the seeds grow, pressure builds. When something triggers the case to split open, the seeds fly out in all directions. Pods of cow vetch snap open when dry Closed pod Blowin’ in the Wind Tiny, light seeds Blowin’ in the Wind The wind plays a role in spreading certain seeds. For example, when he wind blows against the seed head of a columbine plant, its tiny lightweight seeds shake out like salt from a shaker. The seeds usually fall pretty close to where the parent plant grows. Columbine Lift Off Lift Off Parachutes attached to tiny fruits Sometimes the wind carries seeds farther away. Especially if the seed-carrying fruit is designed to travel. Dandelion seeds are enclosed in tiny fruits that have their own feathery parachutes. These parachutes help the seeds float through the air on the wind—sometimes for long distances. Dandelion A Fair Exchange A Fair Exchange You already know that animals can carry seeds on the outside—but they can carry them inside, too! The seeds of a rose plant grow inside fruits called rose hips. Birds and other animals like to eat the tasty rose hips. Seeds then get scattered to different places through the animals’ droppings. A rose hip carries the seeds of the rose plant A rose hip cut in half shows its coated seeds Seed Dispersal Teacher Notes Hitching a Ride Hitching a Ride Did you ever find little pieces of plants, called burs, stuck to your shoes or pants after a walk through a field? Burs are actually the seedcontaining fruits of some plants. They are covered with prickly little hooks that can “stick” to animals (like you!) that brush against them. That way the burs get a ride to wherever the animal is going. When the bur falls off, the seeds inside are released and a new plant gets a chance to grow. Each fruit has many tiny hooks Common burdock Washed Away Lotus seed heads Washed Away The lotus plant uses water to spread its seeds! This makes sense because the plant actually grows in water. Its roots are attached to the mud at the bottom of a pond or river but a long stem carries its leaves and flowers to the surface. The fruit of a lotus plant is a flat-topped pod with holes that hold seeds. When the seeds are ripe, the pod tips down and the seeds fall into the water and float away! Dried lotus seed head from above Hitching a Ride The best way to find out which seeds are dispersed by animals is to go for a walk through rough grassland. You will probably return home with the fruits of a number of different plants stuck to your clothes. Known as “burs”, these fruits have hooks and spines which cling to the fur and wool of passing animals. When the burs are rubbed or scratched off, their seeds fall to the ground and germinate. Washed Away The lotus is a water plant that produces its seeds in a flattened head. When the seeds are ripe, they fall on to the water’s surface and float away. Lotus seeds can be extraordinarily long-lived. Some have been known to germinate more than 200 years after they were shed. Seed held in cup Off to a Flying Start Off to a Flying Start Cow vetch Believe it or not, some plants actually throw their own seeds into the air. How? It’s kind of like what happens when a balloon is filled with too much air. The pressure builds. Finally the balloon explodes and the air rushes out. Some plants, like the Himalayan balsam flower and the cow vetch, grow their seeds in cases. As the seeds grow, pressure builds. When something triggers the case to split open, the seeds fly out in all directions. Pods of cow vetch snap open when dry Closed pod Blowin’ in the Wind Tiny, light seeds Blowin’ in the Wind The wind plays a role in spreading certain seeds. For example, when he wind blows against the seed head of a columbine plant, its tiny lightweight seeds shake out like salt from a shaker. The seeds usually fall pretty close to where the parent plant grows. Off to a Flying Start Some plants disperse their seeds with natural catapults. These work by suddenly releasing tension that builds up as the seed case grows: the seed case splits open, flinging the seeds in all directions. These catapults are triggered in a number of ways. Some, particularly the pods of pea-family plants such as vetches, burst open when the sun dries them. Others, such as the Himalayan balsam are triggered by the movement of the wind or by an animal brushing against the plant. Blowin’ in the Wind Seeds that are dispersed by the wind must be small and light if they are to be carried any distance by the breeze. When the wind shakes the seed heads of plants such as the columbine, the seeds are scattered just a short distance from the parent plant. Columbine Lift Off Lift Off Parachutes attached to tiny fruits Sometimes the wind carries seeds farther away. Especially if the seed-carrying fruit is designed to travel. Dandelion seeds are enclosed in tiny fruits that have their own feathery parachutes. These parachutes help the seeds float through the air on the wind—sometimes for long distances. Dandelion A Fair Exchange A Fair Exchange You already know that animals can carry seeds on the outside—but they can carry them inside, too! The seeds of a rose plant grow inside fruits called rose hips. Birds and other animals like to eat the tasty rose hips. Seeds then get scattered to different places through the animals’ droppings. A rose hip carries the seeds of the rose plant A rose hip cut in half shows its coated seeds Lift Off The seeds of the dandelion are encased in tiny fruits and have their own special feathery parachutes to help them float through the air. A slight breeze is all that is needed to lift the parachutes into the air. They may fall close by, but if there is enough updraft they can be carried for long distances. When a fruit lands, it no longer needs the parachute that has carried it on its journey, and this breaks off. Over the winter the seed sinks into the soil, waiting for the spring when it begins to germinate. A Fair Exchange The rose hip fruit is brightly colored, attracting birds (and other animals) to eat it. Seeds are enclosed in a thin but tough coat-- called achenes. With luck, the achenes will pass through the animal’s digestive tract unharmed and the seeds will be scattered in the animal’s droppings.
