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UltravioletPhotography

The Colorful Queen Anne's Lace (in NIR/SWIR)


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Andy Perrin

I have had occasion to notice that a number of flowers start to show colors again in SWIR, and it turns out that the tiny flowers (florets?? I don't have the vocabulary down, although I'm sure Birna could help) on Queen Anne's Lace have dark centers at 1500nm. The darkening starts before then and is visible also in the longer wavelength parts of NIR. Using the TriWave (which has a germanium-on-silicon sensor with range 350-1600nm), I made the following "true color" IR image from two Omega bandpass filters and a Thorlabs longpass (but effectively a bandpass since it's at the end of my sensor's range of 1600nm).

 

- 1500nm hard coated premium edgepass from Thorlabs (blocked OD5+ through 200nm, which is rather important with the Triwave since it's much more sensitive in visible than at 1500nm+).

- 1064BP25 Omega

- 780BP30 Omega

 

These were placed in the R, G, and B channels respectively to produce the following image:

post-94-0-78031400-1596949530.jpg

 

The image has been processed by registration of the channels, contrast adjustment, noise reduction, sharpening, and boosting saturation.

 

Original images:

 

1500nm-1600nm (but probably mostly 1500-1550nm because the TriWave's gain falls quickly in that range):

post-94-0-19098700-1596949795.jpg

 

1064nm:

post-94-0-54932100-1596949809.jpg

 

780nm:

post-94-0-59364500-1596949826.jpg

 

This result is startling given that in visible and in UV, the flower shows a uniform light or dark appearance, with the flower centers undistinguished from the petals.

 

VIsible:

post-94-0-84916100-1596951323.jpg

 

UV (S8612 1.75mm + UG11 2mm):

post-94-0-40166300-1596951679.jpg

 

--

 

Edited to add a large pano of the whole head at 1500nm. 58 images.

 

post-94-0-14699300-1597037094.jpg

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So interesting! That's why I love SWIR, and I really consider it to be a different band than NIR (I like to put the border at 1100 nm, where the sensitivity of common silicon sensors ends). Basically this flowers (or florets) have something similar to a "nectar guide", but I really doubt there are any animals/insects capable of seeing it. SWIR photons are too weak to induce changes in molecules, at least most molecules, so I doubt that "organic" vision in SWIR is possible.

 

I really hope that in the future, not necessarily the near one, I will have a camera like your TriWave. From UV to SWIR, that's quite a range for a single sensor. Have fun with it.

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Interesting, Andy. I can only get a bit beyond 1000 nm and have yet to see any colour in flowerrs in IR, so it's interesting to see what you are getting at longer wavelengths.

 

As it happens, I've also recently photographed Queen Anne's lace - but in UV. But I was concentrating on the single red (which seems to become black in more mature specimens) flower-ette in the centre of the whole bouquet. (This is what gives the plant its name - it's supposed to be the drop of blood from when Queen Anne pricked her finger while sewing lace. She obviously had too much tme on her hands - perhaps there was a plague lock-down in place at the time.) Anyway, I couldn't get any colour differentiation for this in UV (inc. tri-colour), although it seems to show up as a lighter grey.

 

Dis you happen to get the red flower-ette in your SWIR shots?

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Andy Perrin
Bernard, that's interesting about the name! But now I'm wondering about my specimen because I can't find the red flower-ette.
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Bernard, that's interesting about the name! But now I'm wondering about my specimen because I can't find the red flower-ette.

 

Well the Bible of Wikipedia says "They may be pink in bud and may have a reddish or purple flower in the centre of the umbel." - so looks like the red flower is optional. Certainly your images look like Queen Anne's Lace and so they may well be that, but annoyingly there are plenty of similar-looking flowers (e.g. Hogweed, Cow Parsley). Just for interest, here is a visible light shot I took showing the single red flower-ette in the middle:

 

post-245-0-41673700-1596991409.jpg

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The centre part of the flowers discussed in the opening post is a large nectarium. This structure is widely distributed within the Apiaceae (Umbelliferae).
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Andy Perrin
Thanks, Birna. Hogweed, while it has been seen in Massachusetts, is thankfully rare. It has sap that can cause ugly burns or even blind a person if it gets in the eyes. Cow parsley seems a more likely confusion but the pictures I saw seemed less like the plant I have than the Queen Anne’s Lace.
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It's a problem that a species identity is assumed without it being checked or properly verified. Thus, the plant in question might well be quite another umbellifer than the Daucus carota implied by the vernacular name "Queen Anne's Lace". Cow parsley Anthriscus silvestris comes to mind as a common candidate and there are plentiful of other options within this large family.

 

For umbellifers, to ascertain identity, the flowers themselves are of little diagnostic value. Do provide habit shots (entire plant), foliage, umbels and their supporting bracts (minor and major) and in some cases, the appearance of the fruits can be diagnostic.

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The original specimen is defunct but the rest of the plant isn’t too far away and I suppose I could get a few more shots. I would add that this is not a formal post.
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I understood this post was informal. However, as long as a species name is provided, the search engines will associate your images with that name whether it is correct or not.

 

A better practice is either to ensure a proper ID or just label the species at the family level. for example, an umbellifer or a species in the Asteraceae.

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I took a bunch of shots for you, they will be uploaded soon after resizing and/or cropping. I would rather have a correct ID!
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Okay, here we go. I chose to err on the side of too many photos rather than too few, because it is 34C outside and the plant is a mile away (and I don't drive).

 

First the plant with my iced tea for scale. (That is not litter, and the cup was properly recycled afterwards.)

post-94-0-46023600-1597094834.jpg

 

Next the location:

post-94-0-58535000-1597094891.jpg

 

Flowers from above:

post-94-0-92273400-1597094922.jpg

 

post-94-0-40089100-1597095035.jpg

 

From below:

post-94-0-84937900-1597094974.jpg

 

post-94-0-55318700-1597094990.jpg

 

post-94-0-13829100-1597095015.jpg

 

Stem:

post-94-0-23340300-1597095063.jpg

 

post-94-0-50276500-1597095090.jpg

 

Leaves:

post-94-0-41203000-1597095120.jpg

 

post-94-0-24219600-1597095154.jpg

 

post-94-0-86303200-1597095170.jpg

 

Closed up:

post-94-0-51684400-1597095190.jpg

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Agree with Birna, this is Daucus carota.

The closed up umbel showing spiky seeds is informally called a "bird's nest" and is one characteristic identifier of this flower along with the longish hairs on the main stem and the leaf shape. The other white umbellifers do not fold up when drying in quite that same way and have smooth stems or only slightly fuzzy stems with very different leaves. The dark red center flower is another primary identifier because none of the other white umbellifers have that. I do not know why some umbels of D. carota do not have the red center flower. Just under the main umbel is a cluster of little pointy bractlets, again unique to this white umbellifer.

 

Queen Anne's Lace is ubiquitous in New England this time of year, quite lovely when bobbing in the breezes.

 

Well, enough on the ID front. I really enjoyed seeing the 1500 nm version. It seems to indicate some non-pigment chemical difference between the nectarium and the flower petal, do you think?

 

 

Edit: added "non-pigment". I was trying to say that this seems different from light/dark areas in floral UV signatures which are often/usually pigment based.

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Agree with Birna, this is Daucus carota.

Well, enough on the ID front. I really enjoyed seeing the 1500 nm version. It seems to indicate some non-pigment chemical difference between the nectarium and the flower petal, do you think?

In SWIR some molecules start absorbing again, or simply start absorbing (like sugar). This is also why I like to distinguish it from NIR, in which basically everything becomes white/transparent.

 

Sugar in SWIR: https://www.ultravioletphotography.com/content/index.php/topic/2127-salt-vs-sugar-in-the-swir

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Well, enough on the ID front. I really enjoyed seeing the 1500 nm version. It seems to indicate some non-pigment chemical difference between the nectarium and the flower petal, do you think?

 

Edit: added "non-pigment". I was trying to say that this seems different from light/dark areas in floral UV signatures which are often/usually pigment based.

Heh. I honestly didn't have too much doubt about the ID, because of the hairy stems, but I'm not a botanist.

 

I agree that it's non-pigment based...probably. My reason for thinking that is that the stem also turned somewhat blue-green in the 780-1500nm color pic, although not as blue as the nectarium. I suppose they could have the same pigment, but a more likely explanation might be hydration levels. The water absorption increases dramatically towards 1500nm, so if there is more water in the nectarium then it would look blue here because the red channel is darkest. I'm not sure it's the same situation as in the disc flowers of the cone flower that I imaged awhile ago -- in that case even the dried flower showed a dark disc. I could try a similar experiment here I guess. But it's kinda hot out.

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Well, I think that unless you measure the absorption spectrum with a spectrometer, you will never know what is absorbing. Water may be trapped inside in some way?
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That nectary (center structure) would contain a sugar-water solution of some type - glucose? fructose? sucrose? So I'm thinking it is the sugar as Stefano has mentioned that is absorbing. (Not taking into account what the nectary container is made from though. Must be translucent?)
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