What is seed dispersal?
Seeds need to travel away from their parent plant so new plants can grow in other places. This process is called seed dispersal.
- Some seeds travel on the wind, such as dandelions seeds with their fluffy tops that float.
- Others drift on water, such as coconuts that can cross the sea.
- Animals eat fruits and the seeds in them are spread in the animal's poo.
- Some seeds have hooks that stick to animal fur and get carried away.
- Others burst from seedpods and scatter like tiny fireworks!
Watch: Alternative Plant Disposal
A quiet trip to a garden centre has some pretty explosive results.
JEAN: I don't think there's anything more peaceful than a garden centre, Jackie.
JACKIE: I don't think so. All these lovely plants. Best of all, someone else has to water them.
POLICE OFFICER 1: I need everyone to take cover.
Set up a perimeter from the compost to the cafe.
JEAN: What's going on?
POLICE OFFICER 2: Please get back, this is a hazard zone! Remain behind the wheelbarrow.
JEAN: What are you?
POLICE OFFICER 1: Explosive plant disposal.
JEAN: Explosive plant?
POLICE OFFICER 2: That's right.
It's our job to prevent plants from exploding.
Right now, we're the only people standing in the way of this place going boom. And this place? Not … not going boom.
Here we go, chief.
POLICE OFFICER 1: Chinese Witch Hazel.
POLICE OFFICER 2: What?
JEAN: Oh, it's so pretty.
POLICE OFFICER 2: Sorry.
POLICE OFFICER 1: Pretty explosive more like.
Chinese Witch Hazel has a hard, fuzzy fruit.
When that plant is ready to release its seeds, the outer layer shrinks, squeezing the seeds inside with explosive results.
JACKIE: But why would a plant want to explode?
POLICE OFFICER 2: Because the explosion helps the plant spread its seeds over a wider distance.
The further the seeds go, the less they have to compete with the parent plant for sunshine, water and nutrients.
JEAN: Oh, that is fascinating.
POLICE OFFICER 2: Get back! I've seen these things spray up to 18 metres.
POLICE OFFICER 1: I am approaching the plant.
POLICE OFFICER 2: She's approaching the plant right now.
POLICE OFFICER 1: I am lifting the plant.
POLICE OFFICER 2: She's lifting the plant, over.
POLICE OFFICER 1: I am taking the plant to a safe place.
POLICE OFFICER 2: She's taking the plant to a safe place.
Oh my goodness!
POLICE OFFICER 1: Controlled explosion complete.
POLICE OFFICER 2: Oh, ho, ho ho, you beauty!
JEAN: Right.
JACKIE: Well, if that was all …
POLICE OFFICER 2: Nobody move!
I think we've got another problem.
POLICE OFFICER 1: Is that what I think it is?
JEAN: Do you think it's a pumpkin?
POLICE OFFICER 1: That's no pumpkin, darling.
That is the fruit of the Sandbox Tree.
Once they dry out into seed capsules, they become a ticking time bomb.
POLICE OFFICER 2: … and when they explode they can fling their seeds up to 150 miles per hour.
POLICE OFFICER 2: I'm gonna jump on it.
POLICE OFFICER 1: No!
POLICE OFFICER 1: Save yourself. Oh!
JEAN: Oh.
POLICE OFFICER 1: Oh, okay. That one was just a pumpkin.
Probably put there by someone as a hoax.
POLICE OFFICER 2: Pumpkin hoax, another one.
JEAN: If you want to dispose of anything, maybe you should start with those weeds.
POLICE OFFICER 1: Do you see what I see?
POLICE OFFICER 2: Jewelweed.
JEAN: Oh! Not again.
POLICE OFFICER 1: If anything so much as touches the ripe seed pods on this weed, it burst open, flinging seeds all over the place.
POLICE OFFICER 2: If those seeds hit another pod it could start a chain reaction … meaning…
POLICE OFFICER 1:seed supernova.
POLICE OFFICER 2: I'm gonna cut …
POLICE OFFICER 2: green.
POLICE OFFICER 1: Trust your instincts.
POLICE OFFICER 2: I mean, they're all green.
POLICE OFFICER 1: Nice one.
JACKIE: Hang on. You said the seed pod was the explosive bit so cutting the stalk'll just cause the seed pod to drop and explode.
POLICE OFFICER 2: Oh, no.
POLICE OFFICER 2: No no no no no.
Right back out there!
JACKIE: I'm not sure they were real police.
JEAN: No.
Why do plants disperse their seeds?
Plants disperse their seeds so new plants can grow in different places. If all the seeds grew right next to the parent plant, they would have to share sunlight, water, and space.
As a result, the seeds might not grow well. By spreading out, each new plant gets what it needs to be healthy. This helps plants make more plants and keeps the world full of wonderful greenery.
Horrible Science fact
The impatiens plant disperses its seeds through little explosions! When its seedpods are fully grown and someone touches them, the pods suddenly burst open flinging seeds in all directions. It’s like nature’s own mini catapult.
Find out more about seed dispersal.
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