capillary action osmosis Water in plants water transport in plants
Age Group
14 15 16
Expected time
1 period
Red or blue flowers.PDF
beaker symbol

Red or blue flowers?

What’s the mystery? The teacher couldn’t decide whether to wear a red flower or a blue one, so they decided on a compromise: a half red, half blue flower! But something like that can’t be natural, can it?
Domain(s) Biology
Subdomain keywords Water in plants, water transport in plants, capillary action, osmosis.
Age group 14 to 16 years old.
Expected time for the mystery Approximate time for teacher preparation: 40 min.
Approximate time in classroom: two 45-min lessons.
Safety/supervision No restrictions needed.
Disclaimer: the authors of this teaching material will not be held responsible for any injury or damage to persons or properties that might occur in its use.
Preparation and list of materials White flowers (works best with carnations), coloured ink, glasses/beakers, various materials the students can use for their experiments (see the teacher materials).
Learning objectives Physiology of plants, anatomy of plants, cell biology, osmosis, diffusion, capillary action.
Resources The colouration process takes a long time. You can watch it sped up with two white roses here:

You can see the split colouration of a carnation here: