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Can live flowers absorb dyes?
September 28, 2010 10:17 PM   Subscribe

Can live flowers (as opposed to white coronations in vases) absorb dyes? If so, which flowers and dyes will work?

There is a lot of information online about colouring flowers once cut, but not so much on this!

I'm working on a project on an industrial lot where wastewater containing dyes is diverted to a shored up 'pond'--a very blue pond. If we plant flowers around this pond where they will draw water from it, are they likely to absorb the blue dye, and if so, be harmed by it? What flowers would most readily absorb the colour? This is in NSW Australia, and the dye is of the kind used to colour fibreboard-like materials (to indicate that they are water-resistant and so on).
posted by carnival of animals to Science & Nature (12 answers total) 1 user marked this as a favorite
*carnations, not coronations!
posted by carnival of animals at 10:29 PM on September 28, 2010

I would think that if chemicals in pesticides/ fertilizer/ other pollutants could be absorbed by live plants, that blue dye in pond water could as well. You could experiment by saturating the soil with the dye in a potted version of the flowers you will be planting and see what happens.
posted by Everydayville at 10:34 PM on September 28, 2010

are they azo dyes? If so, check this out:
posted by parmanparman at 10:44 PM on September 28, 2010

I don't think it's very likely that your flowers will turn blue. When you dye a flower in a vase, the water in the vase goes directly to the (dead) flower. A live plant, on the other hand, absorbs and processes liquids and nutrients in specific ways. It's like how healthy people can eat a ton of blue food colouring without turning blue, but if you were to inject blue colouring into a corpse then it would be blue.

On the other hand, non-dye things can make your flowers change colour sometimes in odd ways, like hydrangeas and aluminum.
posted by anaelith at 11:42 PM on September 28, 2010 [2 favorites]

parmanparman, I've been trying to contact the people who make the dye, but without luck -- so I'm not sure what kind of dye it is. Thanks for the interesting article!

(I've asked a good landscape architect about this and have been told this is a question for a plant biologist, and of course that I'll need to identify exactly the dye.)
posted by carnival of animals at 1:29 AM on September 29, 2010

Unless they were aquatic plants I doubt anything would happen. Try this experiment:

Get a plastic soda bottle cut off the top and drill some small holes in the bottom and fill it with a few rocks and then a bit of sand. On top of the sand put some dirt and then some more sand. Take some of the really blue water and pass it through collecting the water that goes through. This is the water that your plants will see and I doubt that it will have any color in it at all. The dyes would be adsorbed onto the surface of the soils and not get access to the roots.

Also I would just collect some of the water and try using it to water some plants and see if the color changes at all. It might but I really doubt it.
posted by koolkat at 2:04 AM on September 29, 2010

If I remember my chemistry and plant biology correctly, probably not. Dye molecules tend to a) relatively complex and large, and b) not strongly bonded to water molecules (the whole point is that they bond to more complex/attractive structures). The root system of plants is highly selective - basically, water passes through the inter-cellular space of roots freely, but is then selectively transported through the endodermal cells into the stele (the 'guts' of the root, part of the vascular system of the plant). Anything else (e.g. minerals, nutrients) is moved by active transport (i.e. highly selective).

The whole purpose of the root system is not just to absorb everything; it's to act as a barrier to anything the plant doesn't want or can't use. It makes no sense from an evolutionary PoV for plants to do anything else 'cos transporting non-essential junk around costs energy, and plants are quite energy-restricted organisms.

The reason dyed water works with cut flowers is that all this selection by the root system has been bypassed; the xylem of the vascular system is directly in contact with the coloured water which is then transported to the petals.

Not saying it's not possible to find some combination of plants / dyes that'll work, but I think it's highly unlikely. What are you trying to do - create a funky-looking border, or use plants as an indicator of seepage from the pond? You might be better off seeing if there's any metal contaminants along with the dye, or what compounds it eventually breaks down to, then look at plants that are sensitive to those.
posted by Pinback at 2:24 AM on September 29, 2010 [4 favorites]

I don't know the answer to your specific question, but you should look into the plants used in bioswales. Both Marrickville and Sydney City councils use them extensively to filter stormwater. Perhaps they can give you more information?
posted by embrangled at 5:02 AM on September 29, 2010

anaelith: Human skin will change colors if they eat a lot of a certain food. Like carrots. My dad used to eat tons of carrots every day because he loved the vegetable, and his eating habits *definitely* turned his skin an unnatural orange color. He wasn't unhealthy, he just ingested a lot of carotene.

Live flowers are similar, but they require *a lot* of the dye, and their petals must be light enough for the colors to show up. People that dye carnations will excessively prune any petals and stems on the flower, meaning the dyed water will go straight to the only thing that's left on the plant, which is the flower itself. So all the dye will be concentrated into one place, and the effects of the dye will appear probably within just a week of feeding the plant only dyed water.

If you use a live plant, the dye will be distributed fairly evenly throughout the entire plant, so it will take a lot longer for the dye to become visible to the human eye, and it won't be as intense because plants will naturally filter out the dye with their roots. You will still seem some color, but some colors more than others, depending on the dye.

So, to answer your question, yes, it's possible, but you probably won't get the same intense results as a dyed carnation, at least not without pruning all the leaves and stems on your plant, thus forcing the dye to go straight to the flower.
posted by nikkorizz at 6:09 AM on September 29, 2010

But the way that carrots colour the human body is different than how dye works. The compounds that "dye" people are produced by the human body because there are lots of a precursor chemical (that also tends to be orange).

I'll second Pinback that it's the free access to the xylem that makes carnations dyable so that mechanism won't work for live plants (roots block dye molecules).

I assume you're looking for flowers for the aesthetic appeal of blue flowers rather than as bioindicators because there probably are a bunch of plants you could use for that. Also be careful of disposing of the dead/dying flowers; because they are picking up the waste water (whether or not they are blue) they are probably considered hazardous waste.
posted by hydrobatidae at 9:25 AM on September 29, 2010

Oh, heck - this is silly! Go outside & pull up a white flowering plant (wild asters & queen anne's lace are blooming right now in the Northern US, but any should do), wash off the dirt, plop it in water with lots of food coloring, and see if it works. Within a few hours, the flowers should start "veining" the color.
posted by IAmBroom at 11:09 AM on September 29, 2010

Hydrangeas will change the colour of their flowers in response to the ph or aluminium levels (see, eg this page). Don't know if that is helpful or not - depending on what the ph of the dye is, it may change the colour of the flowers, but not necessarily to blue. Not sure if that would fulfil what you are trying to do.
posted by AnnaRat at 5:09 PM on September 29, 2010

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