General video · Level B2 - Part 1
Why Do Tumbleweeds Tumble
They're prickly. Restless.
Level: B2 · 35 sentences
Transcript
- They're prickly.
- Restless.
- Rambling.
- But if most plants are perfectly content to stay in one place,
- why does the tumbleweed hit the open road?
- Tumbleweeds start out as tiny seedlings.
- They sprout in late winter.
- By summer the plant takes on its round shape.
- They grow flowers nestled between thorny leaves.
- Inside each flower, a fruit with a single seed develops.
- This fruit is different than something delicious like cherries.
- Lucky for the cherry tree, a bird will carry the fruit away in its belly and disperse its seeds.
- But the tumbleweed takes matters into its own hands.
- Come fall, the plant dries out and dies.
- The seeds are still in there.
- Gusts of wind easily break the dead tumbleweed from its roots.
- See where it was attached?
- It looks kind of like bones.
- A special layer of cells at the base of the plant makes this clean break possible.
- Then the skeleton is off, shaking loose tens of thousands of seeds as it goes.
- It turns out, some living things spread their seeds better when they're dead.
- Like cowboys in a Western, tumbleweeds head out on the open range.
- But these icons of the American West actually come from the east, all the way from Ukraine.
- They're a common weed in Russia too. That's why they're called Russian thistle.
- They might have hitched a ride here in the 1800s hidden among flax seeds.
- Nowadays, they might amble onto the freeway and make you swerve.
- Or get tangled up in your irrigation system.
- They could even roll into your neighborhood, pile up and become a fire hazard.
- But a green lawn isn't what the tumbleweed is looking for.
- It can't compete with plants like grass.
- It needs a barren place like this abandoned onion field north of Los Angeles.
- With each bounce the tumbleweed sends its seeds flying.
- It spreads them out so they all get plenty of sunlight and space.
- The coiled-up embryo inside just needs a little water to sprout.
- And soon enough, this plant will strike out on its own.