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Curious Kids: how can a tiny seed actually grow into a huge tree?
This is an article from Curious Kids, a new series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!
How can a tiny seed actually grow into a huge tree? – Finney, aged 6, from Bairnsdale in rural Victoria.
Tree seeds fall (like the tiny Eucalypt seeds) or helicopter down (like the winged seeds of the Maple) from their parents with a full set of instructions on how to grow.
A single tree may drop hundreds or even many thousands of seeds. Many of these seeds will become snacks for insects or fall where the ground is too hard, too dry, or just not suitable for trees. Some though will fall where the situation is just right!
Just right might mean bare dirt or some nice decayed mulch with enough sunlight.
The seed contains an embryo - a group of cells ready to form roots, a stem and the first leaves. Once the coat around the seed is moistened, the embryo cells expand and burst out in a process called germination.
Time-lapse of seed germination.First, the roots will develop and push out and down into the soil to make sure the new plant can get water. Then the stem cells stretch up to display the first leaves.
The embryo uses food stored in the seed to power its initial growth until the leaves can start producing food. Small seeds don’t have much stored food so they have to fall in just the right spot to be successful. The parent tree has some ways to improve the chances of its seed finding the right spot, like dropping seeds after a bushfire has made the ground bare and free from other plants that would use all the water and nutrients.
For some plants, a bushfire triggers the release of seeds. Flickr/Tatters, CC BYOnce the roots are in the soil and the first leaves are in the sun, the plant is ready to really start growing.
People stop growing after they’ve become grown-ups but trees just keep getting taller and thicker however long they are alive.
Grass, bamboo and many other plants grow from the bottom up, so if you put a mark on the stem and come back in a little while, that mark will have been pushed further above the ground. But if you put a mark or even nail a board into a tree at one metre above the ground then come back in 10 years, it will still be only one metre above the ground. That’s because trees grow from the outside and the top up.
Some trees can grow to be more than 100 metres tall! Flickr/Andrew Malone, CC BYThe newest and outer shell of a tree contains all the living parts of the wood - the parts that move water up from the roots and food down from the leaves. If trees stop growing these outer, living shells of wood, the whole tree dies.
Some trees can grow to be more than 100 metres tall – that’s as tall as a skyscraper! In fact, humans are now building buildings out of wood that are over 50 metres tall and there are plans to go well beyond that.
The tallest tree currently is over 110 metres tall, and scientists think some trees may have been as much as 150 metres tall.
Trees grow from the top up.A problem with getting even taller is that trees use water the same as you use blood - to move the nutrients and oxygen and other vital things around our body. But a tall tree has to move it from the roots to the tip of the leaves. For a 100 metre tall tree, that is like 30 flights of stairs. And a big tree could use more than 200 litres of water every day. Imagine carrying 30 buckets of water up 30 flights of stairs every day!
In our tall buildings, we need huge pumps and generators to move the water to the top, but trees just rely on their amazing structure and a little bit of power from the Sun.
Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:
* Email your question to curiouskids@theconversation.edu.au
* Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or
* Tell us on Facebook
Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.
Cris Brack does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.
London mayor issues emergency air quality alert amid heatwave
Rising temperatures and southerly winds expected to bring toxic air to large parts of England and Wales on Wednesday
The mayor of London, Sadiq Khan, has triggered the capital’s emergency air quality alert as soaring temperatures combined with southerly winds are expected to bring dangerously toxic air to large parts of England and Wales on Wednesday.
The emergency alerts will see warnings displayed at bus stops, on road signs and on the underground.
Continue reading...Australia warned it has radically underestimated climate change security threat
Senate inquiry starts as report into political, military and humanitarian risks of climate change across Asia Pacific released
As the Senate launches an inquiry into the national security ramifications of climate change, a new report has warned global warming will cause increasingly regular and severe humanitarian crises across the Asia-Pacific.
Disaster Alley, written by the Breakthrough Centre for Climate Restoration, forecasts climate change could potentially displace tens of millions from swamped cities, drive fragile states to failure, cause intractable political instability, and spark military conflict.
Continue reading...Ten years ago Turnbull called out Peter Garrett on climate. What went wrong? | Graham Readfearn
After a decade of policy backflips and uncertainty, we are now being sold ‘technology neutral’ energy policy. But we need it to be discriminatory – and favour clean power
Ten years ago today Malcolm Turnbull was getting stuck in to a debate in Parliament House with Peter Garrett about climate change.
Climate change, said Turnbull, was “an enormous challenge and probably the biggest one our country faces, the world faces, at the moment.”
Continue reading...Exxon, BP and Shell back carbon tax proposal to curb emissions
- Oil giants among numerous firms to support conservative group’s plan
- But Greenpeace says: ‘A PR exercise is no cure for decades of deception’
Oil giants ExxonMobil, Shell, BP and Total are among a group of large corporations supporting a plan to tax carbon dioxide emissions in order to address climate change.
The companies have revealed their support for the Climate Leadership Council, a group of senior Republican figures that in February proposed a $40 fee on each ton of CO2 emitted as part of a “free-market, limited government” response to climate change.
Continue reading...