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Monocots fluoresce blueish, Dicots look reddish

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#1 Damon

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Posted 03 March 2018 - 05:04

Has anyone found the above title to be false?
Looking at all my plant pics it is holding true so far. Not including mosses and other weirdos.
Also, I do know that some don't seem to fluoresce at all.

#2 Andrea B.

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Posted 03 March 2018 - 16:14

Damon, which part of the plant are we talking about? Rays/petals or reproductive parts or what?

And true, not everything fluoresces.

I just pulled my fluor photos for another reason, so I'll check them out for this.

To remind folks -- a monocot has one leaf in its seed or bulb while a dicot has two. So when you see seedlings emerge and produce their first leaves, you'll see either 1 or 2. Flowers like tulips, crocus, daffodils, alliums (onions) and orchids are all monocots.
Andrea G. Blum
Often found hanging out with flowers & bees.

#3 Damon

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Posted 03 March 2018 - 20:37

It's kind of confusing but for now mainly the leaves. Any part that has healthy active photosynthesis should be reddish under our UV light sources with dicots.
From my understanding monocots have ferulic acid (a cinnamic acid derivative) which it seems gives them all the blueish fluorescence we have become used to seeing. It absorbs UV and in some cases might be protecting the plant or parts, especially reproductive parts. I was asking because we have so many pics of plants on this site we could confirm this hypothesis.
There is a rabbit hole problem with much of this which is why I am trying to be as simple as possible.


Here is the research I looked over.
https://www.nature.com/articles/srep02738#ref16

https://hal.archives-ouvertes.fr/hal-00885952/document

#4 Andrea B.

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Posted 06 March 2018 - 17:14

Thanks for the update. I have some monocots sprouting up just now, so I will schedule a test of monocot leaves.

I'm not sure we have a lot of monocot leaf photos here? But we can check.

((((I have to schedule things these days! Sigh.....))))

Material: Crocus leaves, snowdrop leaves, daffodil leaves.
Light: 365 UV-Led, 385 UV-Led, Blue Led (if I can find it)
Test: Shoot UV-induced Visible Fluorescence in the Dark.
Include the fluor targets for standardization or results,
but also use Daylight wb for comparison.

OK, it's now written down in the Little Turquoise Book of Speriments.
Andrea G. Blum
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#5 Damon

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Posted 08 March 2018 - 03:35

Thanks for checking it out.
I have read multiple times now in various studies how some nocturnal animals (and now many mammals) can see into UV and like the reindeer you mentioned they are compelling - although regarding truly nocturnal I am at a loss in how there is enough UV at night to be useful for Fluorescence. Also, in the study linked above, bees using Fluorescence as a cue to find grass pollen etc. What I don't know is how they are seeing this fluorescence. These bees are not flying at night (nor are the birds).

Just because something can see in UV does not correlate to seeing blue emissions. Seeing in UV isn't necessary to see UV induced visible fluorescence. I don't see UV and I can see blue emission with the aid of UV light. But during the day it is drowned out by all the rest of the powerful daylight. Somehow the blue, which is in the best detectable range apparently by them, must be especially strong to these creatures and stands out during the day? I am beginning to wonder if heat is detectable from Fluorescence day or night.
I remember shooting a laser thermometer at the giant black UV signature on my Gazanias and it was indeed warmer there. I think I will try check known heavy fluorescing parts and see if they are warmer too.
I am probably missing something and might be talking myself in circles :)

Quite the snow storm we just had Andrea!


Read this excerpt:
"We also observed distinct blue emissions at UV 366 nm from the endosperms of the cereals, millets and bamboos (Fig. 1d, k). Seed predators or dispensers like birds, rats and other small mammals could see these UV induced blue fluorescence emissions16,17,18,19,20,21,22,23. Rats are known fruit predators of bamboos10,11. Rodent and other predation losses of cereals and millets in seedling, grain and warehouse stages are hugely significant11. Most nocturnal species, active in late evenings and in the darkness of the night, have adapted sensitive vision aiding them to find their food and mates17,19,20,21,22,23,24. Even low levels of UV in nocturnal conditions could lead to blue emissions from grass flowers, fruits and seeds. These fluorescence emissions from grass reproductive structures are in the blue region of the visible spectrum, which is the best detectable range for arthropods, birds, rats and other small mammals16,17,18,19,20,21,22,23. These blue emissions from grass flowers and seeds could attract seed dispensers, predators and even insect pests towards them18,20. Under UV, the reproductive structures of grasses are truly ‘showy’."

#6 Andrea B.

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Posted 19 March 2018 - 21:18

Also, in the study linked above, bees using Fluorescence as a cue to find grass pollen etc. What I don't know is how they are seeing this fluorescence.

If the UV in sunlight induces a blue or green emission in addition to any blue or green reflection, then the bee-perceived colour effect could be more intense than it would without the fluorescence. This might enable an easier detection of certain plants. I don't recall at the moment what I've read about bees and colour intensity. I'm just speculating here.

Same could be true for human eyes. During daylight hours we don't have a way to know how much a particular colour we are seeing might be intensified by a simultaneous visible fluorescence emission induced by some miscreant wavelength in sunlight (laughing). For that matter, why couldn't a colour we perceive during daylight hours be all emission and no reflection in a particular wavelength region? We wouldn't know would we? Well, we might learn that if we take the fluorescent thing indoors and it becomes rather dull looking!

So I think that it is not that we cannot see visible fluorescece in daylight hours, but rather that we don't know in what ratios the colour we detect is being produced by emission or by reflection - or by some combo of the two.

The only reason we are photographing in the dark for our fluor studies is that we want to cut all reflected colours so that we capture only the emitted colours. And we humans only know we are seeing fluorescence when in the dark. Doesn't mean it isn't happening during daylight or that is isn't meaningful to some critters.

Hope I phrased this properly, or almost so.

****

Take dichromatic rats......they have a UV/blue receptor and a green one. (Quick internet scan, should be verified.) The various cereals, grains and seeds would be rather dull to rats if UV were omitted from sunlight. They would have difficulty picking out the yellow/brown/beige/tan colours of those materials from many backgrounds because rats don't have visual receptors to detect combinations of red and yellow reflected wavelengths. The grains would "rat-grey" to the rat without UV in the sun. But with the UV-induced blue emitted wavelengths, bingo! those grains become much more visible to the rat.

And of course these animals learn. Once the blue-emission has led the rat to the grain the first time, that rat will know how to get there every night thereafter in the pitch dark to eat that grain until it becomes a little fatty ratty and 'splodes.
Andrea G. Blum
Often found hanging out with flowers & bees.