Biology
Seed dispersal
Plants cannot walk, but their seeds travel far: on the wind, in the fur of animals, or as floaters on the water.
What you need first
A plant stands fixed in the soil in one spot for its whole life. But its seeds should not fall right beneath it, otherwise the young plants would stand in the shade of the mother plant and have to compete with her for light, water, and space. That is why plants have developed astonishing tricks to send their seeds as far away as possible.
By the wind
Many seeds are built so light and fine that the wind can carry them off. The dandelion forms little parachutes of fine hairs that sail through the air. The maple hangs a wing on each seed: as it falls the seed spins like a helicopter rotor, stays in the air longer, and is carried off to the side. The stronger the wind, the farther they get.
By animals
Some fruits are sweet and tasty so that animals eat them. The hard seeds inside are not digested and come back out far away with the animals' droppings, with a bit of fertiliser on top. Other seeds carry little hooks that cling to fur. The burr hangs on to the animal this way and only drops off far away.
By water and by their own spring
Along rivers and by the sea, seeds spread over the water. The thick, fibrous husk of the coconut holds air, so it drifts across the sea for months until it lands on a new beach. Some plants even fling their seeds away themselves: the touch-me-not tenses its ripe fruit like a spring and lets the seeds shoot out at the slightest touch, several metres away.
Exercises
0 of 6 solvedTime to try it yourself. You can't break anything, every attempt counts.
Why should a plant's seeds not fall right beneath it?
How does a dandelion seed travel with its little parachute?
Which fruit floats across the sea for months until it lands on a new beach?
Complete the sentence: the burr carries little hooks and this way hangs on in the … of animals.
The tutorial names four ways of travelling: wind, animals, water, and a plant's own spring. How many different ways is that?
Match each plant to its way of dispersing seeds.