Floral Pigments - some reflectance charts & other stuff

[Andrea B.]

 

This is a bit random. I just wanted to get some stuff posted to link to as needed.

 

SEE below several UV Reflectance Charts for various flowers and pigments.

 

If you copy anything for public use, then please include the source documentation.

We don't want to violate any copyright laws.

 

There are a few UV examples.

 

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FROM:

Introduction to Ecological Biochemistry, 4th Ed.

LINK

by J.B. Harborne

Academic Press, 1993

 

 

 

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BULL'S-EYE

Newer research about bee vision may not agree with the conclusions in this paragraph, but it remains a good explanation about how TWO PIGMENTS are required for a UV-absorbing bull's-eye.

In the Black-eyed Susan (Rudbeckia), the carotenoid pigment reflects yellow and reflects UV.

The flavonol reflects yellow and absorbs UV.

 

 

 

COLOR CHANGES AFTER POLLINATION

We have some examples of this.

 

 

 

 

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FROM:  tba

 

 

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FROM:

Andrea B.

I tried to start making a census of the visible and false colours of the floral signatures in our botanical section. I didn't get too far.

 

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FROM:

Painting the green canvas: how pigments produce flower colors

by Eduardo Narbona, José C. del Valle and Justen B. Whittall

June 2021

Published by Portland Press Limited under CCAL 4.0

 

 

[Andrea B.]

FROM:

Flower Color Evolution and the Evidence of Polinator-Mediated Selection

by Judith Trunschke, Klaus Lunau, Graham H. Pyke, Zong-Xin Ren and Hong Wang

26 July 2021

Frontiers in Plant Science

www.frontiersin.org

(open access, reviewed)

 

 

 

 

[Andrea B.]

FROM

Floral UV Features of a Plant Species from a Neotropical Savanna

by Priscilla Tunes, Maria Gabriela Gutierrez Camargo and Elza Guimarães

May 2021

Frontiers in Plant Science

wwwfrontiersinorg

(Open Access, Reviewed)

 

Excerpt 1:

Of 80 plant species, ca. 70% were UV-patternless, most of them UV-absorbing. Approximately 30% presented one of three types of UV-patterns: bullseye, contrasting corolla markings oriented toward floral resources or contrasting reproductive structures, which were all considered as floral guides.

 

Excerpt 2:

UV- patterned flowers were mainly associated with bee-pollination.

UV-absorbing flowers comprised the only category with hawkmoth- and butterfly-pollinated flowers, and a high percentage of hummingbird-pollinated species.

Nocturnal pollinated species were also commonly UV-absorbing, except for one UV-reflecting bat-pollinated species and one beetle-pollinated species with UV-reflecting stigmas.

 

Excerpt 3:

...still little is known about the evolutionary history of UV-patterns (Koski, 2020).

 

Excerpt 4:

We photographed the UV reflectance of one to three flowers and inflorescences of 80 plant species (Supplementary Table 2) in studio conditions. For that, we used a hand-held UV light source, which emits light from 315 to 405 nm, with a peak at 365 nm, to illuminate the flowers. We excluded all human-visible light by using a camera with a modified sensor that only captures UV light from 340 to 400 nm, which corresponds exclusively to the UV portion of the light spectrum. In addition, this range corresponds to the spectral sensitivity of the UV-photoreceptors of a large variety of Hymenopteran pollinators (Chittka, 1992; Peitsch et al., 1992; Skorupski et al., 2007; Skorupski and Chittka, 2010), bird pollinators (Herrera et al., 2008; Ödeen and Håstad, 2010), and bat pollinators (Müller et al., 2009).

 

Excerpt 5:

To collect the reflectance data, we used a spectrophotometer (Ocean Optics Jaz-EL200 UV-VIS) which collects reflectance data from 200 to 890 nm including the UV and human-visible wavelengths. We considered UV-reflecting when a given floral part reflects more than 5% between 300 and 400 nm, the UV- band.

 

Excerpt 6:

We classified the 80 observed plant species, belonging to 68 genera, in 29 families, into five categories, based on floral UV features:

• (R) UV-reflecting
• (A) UV-absorbing
• (BE) bullseye
• (CM) contrasting corolla markings oriented toward floral resources or reproductive structures
  • UV-reflecting markings in a flower with predominantly UV-absorbing corolla,
    and vice versa.
• (CR) contrasting reproductive structures
  • UV-reflecting reproductive structures in a flower with UV-absorbing corolla,
    and vice versa.

 

 

 

 

 

 

 

 

 

 

 

 

[Andrea B.]

FROM

Vividly coloured poppy flowers due to dense pigmentation and strong scattering in thin petals

LINK

by Casper J. van der Kooi and Doekele G. Stavenga

January 2019

Journal of Comparative Physiology A

 

Use the blue line for the reflectance of the "face" of the flower.

 

The distal area of a petal is that near the outer edge.

The proximal area of a petal is that near the center of the flower.

If the proximal area of a petal is UV-absorbing, then the typical UV bull's-eye is present.

 

 

FROM

How to colour a flower: on the optical principles of flower coloration

van der Kooi CJ, Elzenga JTM, Staal M, and Stavenga DG. 2016.

Proceedings of the Royal Society B: Biological Sciences, 283(1830): 20160429.

https://www.researchgate.net/publication/302978758_How_to_colour_a_flower_on_the_optical_principles_of_flower_coloration

 

 

 

 

[ulf]

Thank you Andrea!

This is very interesting for understanding the different results we see with UV-pass and different BUG-like stacks.

 

IMHO this thread should be pinned in some easily accessible part of the forum as a vital reference information.

 

 

[colinbm]

Very good Andrea
Such a lot to learn.
It is good that they have taken the results down to 300nm, they must of had us in mind....?

 

[dancingcat]

yes please sticky all of this.. I'm going to want to go back to it often...  thank you.

[Fandyus]

I also think this should be stickied.

[Andrea B.]

We have so many Stickies!!

But, yes, I will Sticky this.

 

If you find anything at all like the preceding stuff, then please do feel free to add it here

together with complete source documentation (as shown above).

 

I'm workiing on adding links to the complete papers. 

[Andrea B.]

Update:  BULL'S-EYE 

Look in the first topic to see the explanation of a UV-absorbing bull's-eye in Rudbeckia, the Black-eyed Susan flower.

 

Update: COLOR CHANGES AFTER POLLINATION

Look in the first topic.

[Yves W]

THANK YOU SO MUCH Andrea

Great work very interesting

[cazza132]

Thanks Andrea - very interesting!