Hibiscus rosa-sinensis [Tropical Hibiscus]

[Andrea B.]

Blum, A.G. (2022) Hibiscus rosa-sinensis L. (Malvaceae) Tropical Hibiscus. Flower photographed in visible and ultraviolet light. LINK

 

Middletown, New Jersey, USA

24 September 2015

Cultivar

 

Synonyms:

• Hibiscus arnottii Griff. ex Mast. 
• Hibiscus boryanus DC. 
• Hibiscus cooperi auct. 
• Hibiscus festalis Salisb. 
• Hibiscus liliiflorus Griff. ex Mast. 
• Hibiscus rosiflorus Stokes 
• Hibiscus storckii Seem.

 

Other Common Names

• Chinese Hibiscus
• China Rose
• Hawaiian Hibiscus

 

Comment:

I'm going with a general classification of this particular plant as H. rosa-sinensis, but I think it is likely to be some kind of hybrid commonly supplied to garden stores to be sold as short-lived, potted, summer annuals to grow on the porch.

This Hibiscus was interesting to photograph in UV because it is very UV-reflective. Most red flowers I have photographed are UV-absorbing.

 

Gear[ D600-conversion + UV-Nikkor 105/4.5 + Sunlight ]

 

Visible[ f/11 for 1/30" @ ISO-200 :: Baader UVIR-Cut Filter ]

As I wrote elsewhere: This flower is scorching red!

 

 

UV[ f/11 for 15" @ ISO-200 :: BaaderU UV-Pass Filter ]

Not only is this Hibiscus UV-reflective, it shows two false colors.

 

 

 

UV+Blue+Green[ f/11 for 1.6" @ ISO-800 :: UG5(1.5mm) + S8612(1.75mm) ]

[nfoto]

I only had geese for dinner in my visits to the Czech republic ... Likewise in all other East European countries I've been to over the years.

[Guest]

UV+Blue+Green is very cool!

[dabateman]

Absolutely beautiful.  I think I used to have some of these in my garden,  before, they got killed when the bushes were all pulled out for cedar trees.

I miss some of the interesting flowers.

[Andy Perrin]

Very pretty Andrea!

[colinbm]

Great collection Andrea

[Wayne Harridge]

Impressive!  For a particular species, do the UV "colours" correspond in any way to the visible colours? 

[nfoto]

No.

[Andy Perrin]

Wayne, to expand on that “no,” you can find examples of species that are all yellow in visible light but have yellow and blue in UV. So there is no 1 to 1 mapping that will work. 
 

In fact the above Hibiscus is like that. It’s red everywhere in visible but blue and yellow in UV. So you can’t map red to any particular color in the UV. 

[Andrea B.]

I disagree. I know why you both said "no", but that is not an entirely accurate answer.

 

The underlying pigments in a flower and the flower petals' surface structure determine its response to incident Ultraviolet light. But we usually don't have that information about a flower. 

 

You would also need to know about a particular flower's bio-chemistry. It is all quite fascinating.

 

Here is a discussion of pigments in Hibiscus: LINK

[nfoto]

The Asteraceae offers plenty of examples of yellow flowers that can appear white, yellow, gray, or black in UV.

[Andy Perrin]

Andrea, you must be misinterpreting the question somehow. There is no way to make a table with visible colors in one column and UV colors in the column next to it. Yes, the pigments in the flower do determine these (in addition to structural colors) but some of those pigments may be transparent in visible light and only absorb in UV. 
 

It’s always tempting to say, for example, “all yellow flowers with five petals will have a UV bullseye” but we know from experience that this is not the case. 

[Andrea B.]

Yes, you could do this if you knew what the pigments were and whether or not they were UV-absorbing or UV-reflecting.

[nfoto]

There are too many unknowns at play here. That is why we continue to be surprised when we do a new flower in UV. Fortunately, to my way of thinking. Otherwise all the fun and excitement would have vanished.

[Andrea B.]

For example, there are at least 6 ways for a flower to be yellow:

carotenoid, flavenol, anthochlor, carotenoid + yellow flavonoid, quinones, betalain alkaloids (in some Caryophyllineae)

Reference:

Biochemistry of Plant Pollination

J.B. Harborn, 1993

in Intro to Ecological Biochemistry, 4th Ed.

 

But the coloration is much more than just the presence of a pigment. For example, the flower's biochemical processes can alter its color after pollination. (We've had a few examples of this.)

[Andy Perrin]

Andrea, the point is that we do not know what the pigments are OR any of the rest of that. So there is no way to map visible to UV, and it’s known to be not 1-1. So the answer is “no” as Birna said. 

 

Another way to say this is: nobody can (even in principle) write a computer program that would take a visible picture of a flower and spit out the corresponding UV photo. You cannot determine the pigments from the color for exactly the reason you pointed out: there are 6 ways to be yellow!

[Andrea B.]

You cannot determine the pigments from the color.........

 

Uh, Andy, I said nothing about determining the pigments in a flower from its color.

I said that IF you knew what the pigments were....

(Go back 4 posts to see that.)

 

We do actually know what the pigments are in many, many flowers. There are a skazillion papers out there which describe exactly that. I've been recently reading 

Blue Flower Color Development by Anthocyanins

Yoshida, More & Kondo, 2008

in Royal Society of Chemistry

 

(If you see a blue flower, you can guess anthocyanin and be right most of the time.

But there are a lot of different types of anthocyanins.)

 

[Andy Perrin]

Andrea, the question was, “For a particular species, do the UV "colours" correspond in any way to the visible colours?”

 

And the answer is no, you cannot turn visible colors into UV colors because some areas of the same flower will show UV colors that do not correspond to the visible ones. Even if you know the pigment (which mostly you don’t) you don’t know its distribution on the flower. How would you have anticipated the UV blue on the hibiscus above? Or where it would appear on the petals?

[dabateman]

Also no because it depends on the camera's false UV colors.  Are you using Andrea's magic Panasonic s1r with different UV false color pallet or the typically Sony sensor based color pallet? 

[Cadmium]

Andrea, Beautiful photos! 

[Andrea B.]

Thank you, Cadmium.

[Andrea B.]

David, the S1R is not unusable w.r.t. its false color palette. False yellows and blues still occur. There seems to be more dark green or cyan in foliage. The Hibiscus above was photographed with my old D600-conversion before its oil-flinging got out of hand.