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UltravioletPhotography

Carnations smell so good!


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The interesting thing for me here is the foliage.

This is a pot of small carnations (I always love how those smell), with some kind of wild daisy I picked stuck into the pot, and some kind of tiny yellow wildflower I stuck into the pot.

See how much different the color of the carnation stems and foliage are compared to the other wildflower stems. The wildflower stems are how I might expect them to look in UV, dark,

but the carnation stems and foliage are somewhat golden. You might ask me what UV filter I used... but this is not a red/IR leak causing the warm carnation foliage.

 

Visual

post-87-0-45109500-1466053368.jpg

 

UV

post-87-0-30412700-1466053408.jpg

 

Schott BG24A 5mm + S8612 2mm (AKA: Eugeniya U, version 2)

post-87-0-76660000-1466053429.jpg

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I do love seeing mixed bouquets of flowers in UV. Those carnations are pretty in UV.

That's a big white Oxeye Daisy and probably a small yellow Lapsana.

 

Good observation about the stems in UV. Yes, there are indeed green foliage, stems and branches which are more UV-reflective instead of UV-absorbing. In the case of the Dianthus (carnations, pinks, sweet william, etc.) the stems and foliage often have a waxy, whitish cuticle which looks like a thin film or "bloom". I'm pretty sure that is what causes the reflective appearance in UV.

 

See the Wikip entry Epicuticular wax for all the chem details. (It took me a while to find that because I couldn't remember what this was called.)

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I'm not sure I recall that buttercups have a whitish bloom? Do you have an example?
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Interesting about the Epicuticular wax.

The carnation came with a tag that says it is 'Deer Resistant'.

post-87-0-05475000-1466216525.jpg

 

Could there be some connection between the Epicuticular wax and what deer avoid eating?

https://journals.uai...nload/8967/8579

 

I have tested these carnations with some of my deer here, and they will not touch it, yet they eat everything around it.

Photo of deer test group:

post-87-0-96428500-1466216509.jpg

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That linked paper shows that for the tarbush, the wax chemistry does put off the deer. So it seems reasonable to extend that idea to the waxy carnation foliage. The deer just don't like the taste.

 

Love your Deer Test Group!

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Andrea, Thanks.

Yes, that study is about a different plant, but suggests a link between the Epicuticular wax and plant consumption.

"Epicuticular wax concentration was greater on the surface of low-use plants.

Approximately 20% more epicuticular wax was present on leaves of tarbush plants receiving low use than on plants browsed to a greater extent."

 

Quoted from:

https://journals.uai...nload/8967/8579

 

This make me wonder what the tarbush plant foliage looks like in UV.

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Andy Perrin

I'm not sure I recall that buttercups have a whitish bloom? Do you have an example?

They are waxy, but not whitish. I wondered if it was the same stuff, just not as thick.

post-94-0-58953000-1466269583.jpg

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The buttercup petal shine is caused by light reflection off the surface conical cells. The reflection is enhanced by the particular layered construction of the buttercup petal. While the buttercup petal is often described as "waxy", we will have do further research to determine whether there is any actual wax. There are some references below which I had gathered in the past (bolding mine).

 

The end (distal) portion of a buttercup petal is also water repellant, while the center is not. This is thought to have something to do with rainwater pollination. The water rolls to the center, maybe makes a mini-pond, and moves pollen onto the stigma. Cool, eh?

The water repellant portion of the petal does seem to indicate possible "waxiness", but there can be other reasons for something not being water absorbent.

 

1) Vignolini et al. (2011) Directional scattering from the glossy flower of Ranunculus: how the buttercup lights up your chin. Journal of the Royal Society Interface, v9 no71 pp1295-1301.

2) 4. Whitney H. M., Kolle M., Andrew P., Chittka L., Steiner U., Glover B. J. 2009. Floral iridescence, produced by diffractive optics, acts as a cue for animal pollinators. Science 323, 130–133 (doi:10.1126/science.1166256)10.1126/science.1166256 [PubMed] [Cross Ref]

3) Gorton H. L., Vogelmann T. C. 1996. Effects of epidermal cell shape and pigmentation on optical properties of Antirrhinum petals at visible and ultraviolet wavelengths. Plant Physiol. 112, 879–888 (doi:10.1104/pp.112.3.879)10.1104/pp.112.3.879 [PMC free article] [PubMed] [Cross Ref]

4) Whitney H. M., Bennett K. M. V., Dorling M., Sandbach L., Prince D., Chittka L., Glover B. J. 2011. Why do so many petals have conical epidermal cells? Ann. Bot. 108, 609–616 (doi:10.1093/aob/mcr065)10.1093/aob/mcr065 [PMC free article] [PubMed] [Cross Ref]

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Andy Perrin

Thanks, Andrea. That first paper (Vignolini et al.) has the explanation. It says there is a yellow starch layer followed by an air gap and then a transparent epidermal layer.

The yellow colour of the specular signal arises from the fact that the light path (ii) traverses the carotenoid pigment-bearing epidermal layer twice, where light in the 400–500 nm range is strongly absorbed. The air gap separating the epidermal from the starch layer is instrumental for the high directional reflectivity because it provides a second planar interface from which light is specularly reflected.

So there is no need for a waxy chemical (or even the conical cells) to get the glossiness, just a transparent epidermal layer and an air gap. That article makes the analogy to coated vs. uncoated white paper.

 

Actually the conical cells give rise to a non-directional response. They discuss the rose here, which does have the conical cells:

As in the majority of flowers, the adaxial epidermis of the rose is characterized by conical papillate cells [13,21] (electronic supplementary material). For the rose, we observe a diffusive scattering of light without an increase in signal in the specular direction.
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[Edit: I globbed up this post somehow when I hit the save button. So will try to restore.]

 

Yes, I forgot that buttercup epi is flat celled? Somewhere that is in a reference. But I'm becoming overladen with flower references. An interesting state of affairs as I'm only an Amateur Botanist. Apropos of which I note that I've run across some quite amazing work done by amateur botanists in taxonomy and some other areas. I wish I had time to perform a "real" botanical study.

 

I crossed out the conical part above.

 

If you run across why the petal is "water resistant", let me know! I know I have that somewhere too.

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Found it finally. Aha!!! WAX!!!

 

Photonic Structures in Plants

by Vignolini, Glover & Steiner

 

This is Chapter 1 in the book Biometrics in Photonics (2013) edited by O. Karthaus.

And all 15 pages of this chapter are available in Google books.

https://books.google...epage&q&f=false

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Andy Perrin

Ok, so that one seems to be saying that the glossiness is from the wax in the epidermal layer. The setup looks like (light coming from above):

 

 

air

-----

waxy yellow epidermis

--

air gap

--

starchy non-directionally reflective white substrate

 

So there are two wax/air interfaces (above and below the epidermis) that would strongly reflect in a directional way because of the difference in refractive index, like partial reflections off a window at night. Now the question is, what IS the wax? Is it the same stuff as in the other flowers with brightly reflecting wax? And are they reflecting for physical reasons like this one or because the wax scatters the light randomly?

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Good questions all. Someday when I have time........... :D

 

******

 

Cadmium, we veered off topic a bit. But that happens here sometimes - one post inspires another inspires another and so on.

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