Changing Colour Flowers with Transpiration!

So you have some white flowers but actually wouldn’t they look good with a bit of red in them? Or maybe blue? Not only are they pretty but can be used to demonstrate transpiration.

Coloured carnation

How could you do this? Well with what looks like a little bit of magic and a huge dollop of science!

Get your lovely white flowers – carnations are a good one to use! (Obviously mummy’s I do these flower experiments for you too!)

Strangely celery also works really well!

Changing colour flowers Science sparks

Place your celery into the food dye in water

Trim them at the stalks

Get your vase and fill with water – add some food colouring of your choice.

Place in your flowers and wait.

Usually you can see effects within a few hours!

Be generous with the food dye!

coloured carnation

This one is yellow and black!

The science bit

The reason this happens is because of something called the transpiration stream. This is the movement of water up the stem of a plant from root to leaf when water is lost from the plant due to evaporation occurring at the leaves. Firstly water is absorbed by the root and moves through root hair cells via the process of osmosis (we will look at this another day!). It then moves into the xylem vessel which is the tube that carries the water up the plant. Plants are not like us with pumping mechanism that pushes our blood around, so water moves up the vessel by adhesion (being attracted to the side of the vessel) and cohesion (water molecules being attracted to each other). Therefore when water evaporates from the top of the leaves it changes the pressure in the vessel and pulls up the column of water to replace the water lost.

The best way to consider this is to imagine you have a thick shake – the straw can’t carry the shake up it, but if you suck from the top, you change the pressure and force the shake up the straw. It moves in a column because the molecules are attracted to each other.

 

 

There are 41 comments

    1. ScienceSparks

      I think the stem structure can vary somewhat and only certain flowers work effectively. Definitely try carnations next time!

    1. ScienceSparks

      Is that a Sat or a Sunday? Can you send us the link, as that would be great! Thanks for stopping by, we are so pleased you like it! :)

  1. mummiafelice

    I don’t know of a child that doesn’t find this utterly fascinating! It’s such a great idea! I have to have a go at this with Little One!

    Thank you for linking up to #handmadethursday x

  2. Christy

    Wondering…If I dye 6 carnations, seperately, a different color each (like the colors of the rainbow), could I then combine them in one vase of plain water after the petals have changed color?

  3. Why do plants need water? | Science Sparks

    […] Transpiration is the process by which water moves up the stem of a plant from root to leaf when water is lost from the plant due to evaporation occurring at the leaves. This continual flow of water and nutrients  keeps the plant’s cells firm, if the cells become short of water they lose firmness and the plant starts to wilt. […]

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