Flowers don’t have a heart or circulation, but they do need a transport system in order to move nutrients, water and waste around. They use tissues in which are specialised for transporting substances through plants over long distances called vascular tissues. One tissue is used to transport inorganic nutrients upwards through the plant, it is called the xylem. The other tissue transports sugars in which are produced in photosynthesis and other products throughout the plant, it’s called the phloem. Within the stems of the plant, the xylem and phloem form vascular bundles. The vascular tissue is easily visible in the leaves & flowers.
The carnation (Dianthus caryophyllus) is a type of flower in which uses these vascular bundles in order to nourish themselves, so that they can perform photosynthesis.
Aim: To investigate how a plant absorbs water.
Hypothesis: If the carnation absorbs the coloured water, it will show the pathways in which water is transported throughout the stem.
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Carnations (a bit of the end cut off diagonally)
Food dye (blue, red, green)
Carnations were placed into separate jars containing water each dyed with a different colour (blue, red green). The carnation stems were each cut 1 cm diagonally at the bottom to ensure the most efficient method of water transport. The carnations were then left in the jar over 24 hours near a window; they were enriched with sunlight. After 24+ hours, the results of the colour pigment and rate of absorption were measured by:
How pigmented the flower was
The amount of water in which was still in the jar after 24h (measured by cm).
– Precaution should be taken when knives and food dye are being used.
Dependent Variable: The distance in which the water travelled through the plant.
Controlled Variable: The jar, amount of water, carnations, brand of food dye, place where they were kept.
After 2-6 hours of being in the dyed water, some flowers clearly showed dyed spots near the edges of their petals. The 3 plants were also showing streaks across the petal. By 24 hours the flowers gained an overall dyed hue due to the pigment of the dye, in which darkened a little over the 24 hour mark. The stems also became slightly dyed in places, especially where the leaves branched off. When the stem was split, the inside was dyed with the colour of the food colouring. This showed that there was movement of water within the plant and the water levels of the jar decreased.
After 24 hours, the jar with blue dye reduced by 2cm, the red jar reduced by 1.4cm and the green jar reduced by 1cm.
The blue dye was absorbed the quickest, and then the red, then the green. The blue dye was also the most vibrant out of the 3 and the green dye was the most vague.
The carnations used the vascular bundles in order to perform osmosis – the movement of water from a high concentration gradient to a low concentration gradient. The xylem inside the stem provide a pathway in which draws water up and provides nourishment to the plant. This was evident due to the visibility of the dye throughout the stem, especially the petals. The movement of the water up the plant was caused by transpiration and cohesion. This can be metaphorically compared to sucking on a straw. Transpiration causes so that the plant can regain the water it originally lost through evaporation. The “suction” is due to the water molecules sticking to themselves due to the vascular tissues being very small. The movement of water up the small tissues is called capillary action.
The water evaporated through openings within the plant are called the stomata. The stomata are “pores” on the epidermis of the plant’s leaves that can open and close, but most importantly, allow for transpiration ; gas exchange. The act of transpiration is the reason why the pigment of the dye is visible on the plants surface, e.g. petals and leaves.
When the plant was split, it was proven that the vascular bundles ran across the stem through the water to the petals of the flower.
The fact that the jar containing the flower was left near the window, sunlight was available and it assisted to speed up the process in which water was absorbed into the plant and the dyeing process.
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The dye worked best with warm water since heat acts as a catalyst. The warmer air temperature would have also sped up the water absorption and dyeing process. This will alter the absorption rate of the plant depending on the time of day, in which will affect the results. Different color dyes seem to work at different rates due to the chemical properties of the dye. Also, different brands of food coloring also affect the rate of color absorption. The place in which the carnations were purchase would have also affected results as they could have been in full bloom, or nearly at the point where they’re wilting.