This week it is our absolute honour to welcome Michael Holland, the author of 'I Ate Sunshine for Breakfast' to join us.  His account of why plants need water in it's many forms is truly fascinating - and so joyfully explained! 

His DIY Oobleck (or corn flour slime) will keep your little ones entertained (and completely baffled) as it is seamlessly moves between being both a liquid and a solid. Time to bring science into the kitchen, the best way of learning. 


Water: an amazing substance!

By Michael Holland, author of ‘I Ate Sunshine For Breakfast – a Celebration of Plants Around the World’

We live on a planet called Earth, but I really think it should be called the Planet Water, since about 71% of our wonderful world is covered in it. About 97% of the world’s water is in the form of sea water, 2% is frozen as ice caps and glaciers and the remaining 1% is ‘freshwater’ (20% of this is in Russia’s massive Lake Baikal).

Made of just 2 parts Hydrogen and one part Oxygen, water is one of the reasons life was able to start on our planet in the first place – in warm, shallow tropical seas – with plenty of time (about 4 billion years) to gradually evolve from tiny plants into all the almost 10 million species of living things on Earth who all need water to survive.

Just as we're part of a food Web - relying on green plants for our energy (the reason I called my book ‘I Ate Sunshine for Breakfast’), we're also a part of a global water cycle – where rain and snow fall onto land, seeping through the soil where bacteria, fungi and small animals filter and clean it while it makes its way into streams, rivers, seas and oceans, all the while evaporating upwards into clouds to rain down again.

Some of the soil water is sucked up by all types of plants which helps them to survive, as water is one of the ingredients of the amazing process called photosynthesis (literally building with light) along with the gas carbon dioxide and minerals from the soil.

Plants lose water through their leaves and this becomes water vapour to join the clouds as well as steamy areas above forests (some of these have been described as gigantic floating rivers and lakes of water vapour).
Devastating and powerful tropical storms are fuelled by the evaporation of sea water in warm parts of the world – so on one hand, the global water cycle keeps us alive and on the other hand, it can take away lives. Since, due to climate change, the temperature of the oceans are rising, these storms might become worse and more frequent.

Welcome to the jungle!

In some tropical places, the total rainfall is more than 2 metres every year!

One of the problems of being a plant in a very rainy place like this is that if leaves get too wet they will go mouldy and if a raindrop stays on a leaf she the sun comes out, it can act like a magnifying glass and burn the leaf,  so it's a good idea to have shapes to divert the water to the ground where it is more useful to the roots. Many tropical leaves are large and waxy with gutters down their centres and pointed ‘drip tips’ at their ends to keep the leaves as dry as possible.

In the deserts of the world, it rains less than 25cm/year and plants here have to either be good at growing with very little water, storing it inside themselves or a bit of both. Desert plants that are swollen with water in their stems or leaves are called succulents and they can go for up to 100 days without a drink. The most famous examples of this are the cacti originally from north, central and South America. In their case, the green, fleshy bit is the thick stem which is swollen with water inside and the leaves have been reduced to prickly spines to protect the precious water inside. These spines are usually white and sometimes very densely packed to reflect sunlight - like a natural sunscreen.

Travelling by water

Seeds need to get away from their ‘parents’ and ‘siblings’ to give them a better chance of survival so they are not competing for light, nutrients, water and space. Some travel by air, others using animals as vehicles, but many rely on water to get to a new home.

One of the classic examples of a water dispersed seed is the coconut. These giant nuts growing in tropical regions are equipped with their very own fibrous life jackets (the husk) to keep them afloat and safe from the salt water of the oceans and seas of the world. Floating, they can survive for up to four months and may have travelled hundreds of kilometres. They can be seen growing just above the high water mark of many tropical beaches.

DIY Oobleck (or corn flour slime)

This is your chance to make something to play with that is both a liquid and a solid at the same time! Known as a Non-Newtonian Fluid, Oobleck (named in the 1949 Dr. Seuss book ‘Bartholemew and the Oobleck) is simply made from corn flour and water (and a little food colouring if you like).

You’ll need to mix 1.5 part of corn flour to 1 part of water (by weight), for example 90g cornflour with 60g water and stir together so they are completely mixed. Once this is done, you’ll be able to pick it up and play with it, but if your hands stop moving, it’ll flow through your fingers. Also, if you hit it, it will crack and snap like a solid – weird water!

Michael's made a YouTube video to show you how to do this:So there you are – just a few watery facts to whet your appetite to find out more!