trees and other plants grow at right angle to the earth. what makes them do this. hal?

Answer 1

Virtually all photosynthesising plants grow towards the light. To get the most amount of light from the sun over a day plants generally grow directly upwards. I remember an old science experiment back in school where we put a bean to germinate in the centre of a cardboard tube that was stored horizontally. The resulting spout grew towards the ends of the tube, growing towards the light and not directly upwards.

Answer 2

It's a combination of geotropism & phototropism.
As to the issue of right angles, if you look at forests on mountain sides, the trees do not grow at right anngles to the earth, they are always vertical though.
The gravity makes sure the trees grow up rather than horizontal, the phototropism makes sure they grow to get maximum light.
If you look at any plant, the branches grow horizontally though, to maximise the light collecting area.
In Rhizome and runner plants, the roots are definately horizontal to enable the plant to spread out.
As to mechanism, In geotropism, if the stem is horizontal, the auxin collects in the lower part, This accelerates growth, forcing the stem to turn up and correct the angle of growth (look at how stems of a fallen plant change angle.
Hope that helps.

Answer 3

Of course not all trees grow vertically and some have a considerable lean to one side (perhaps because the roots provide uneven support). However it takes less energy (force) to support a weight vertically from below. Stand with your hands straight out against a wall then take up the position of a push-up (at the top). Which position can you more easily hold for hours? Main supports for bridges must be as vertical as possible to conserve on material. Once a fence begins to lean gravity may quickly finish the job because the weight is not balanced on its base. A tree grows stronger by bending in the wind from the roots to the top just like our legs grow stronger if we use them. Tall well balanced vertical trees have survival value that can be passed on by seeds. Leaning trees will fall down or get less sun in the shadow of tall trees and will pass on less seeds. Corn growing at a 45 degree angle would be easily beaten down by the wind and rain.

Answer 4

Hi Hal.

The process that makes plants do this is called photo-tropism. The surface of the earth is so vast that from most standpoints it appears flat. From a plant's point of view it is and its light source is generally overhead - the sun. So the plant is drawn upward from the horizontal earth surface to the sun directly above.

Plants will indeed grow towards any light source available and can be made to grow in any direction towards available light.

Here's a couple of links on the technical stuff:
http://en.wikipedia.org/wiki/Phototropism
http://www.biologie.uni-hamburg.de/b-online/e32/32b.htm

Hope that sheds a little light...

Answer 5

They grow towards the light for the most part. In General, the light is always up. In a controlled environment where the light source is fixed in a position adjacent to the plant, it will grow in that direction.

Answer 6

First of all, I think it depends on how they are planted! --- one of the new trees in our garden grew at an angle till it was dug up and replanted.

Some plants in a densly potted area will grow up or out depending on where they can find light and water. --- sunflowers are an example of growing up to find the sun...but they grow faster than the others ...so get there first.

Answer 7

Unfortunately some of the trees in my garden don't know this is how they are supposed to grow.

Answer 8

because the stimulated by sunlight and it called phototropism.
and it also because of thigtropism and meaning stimulated at gravity.

Answer 9

At a guess it could be geotropism.