James Rogers, of Kaiapoi Borough School, asks :-

How do trees drink?

John Walker, a botanist at the University of Canterbury, responded.

Trees and most other plants drink through their root systems.

Rain falls on to the ground and the rain water slowly percolates through the soil surrounding the roots. No doubt you will have noticed that trees have elaborately branched roots which penetrate through the soil to provide a large water-absorbing system and which also anchors them into the ground to stop them falling over.

If you look at the smaller, thinner, ends of a root through a magnifying glass you should be able to see that it is covered with tiny 'root hairs' which actually do the job of absorbing water from the soil. Not only does this give the tree a drink but the rain water dissolves mineral nutrients, like phosphates and potassium from fertilisers, from the soil and these are important 'foods' for the tree helping it to grow big and healthy. In one sense we could say that the rain provides a tree with both food and drink.

If a plant becomes thirsty because it cannot get enough water it begins to wilt and its leaves becomes soft and floppy until eventually it dies. This is why we water the garden to keep the plants healthy and why farmers irrigate their crops.