Flower Census: Update -> Color to False Color Correlation Post #2

[Andrea B.]

Birna and I have wanted to categorize the UV-signatures in the botanical section for years. We just never seem to find the time. I gave it a try yesterday for the Asteraceae family posts. Here is a JPG conversion of part of my Excel spreadsheet.

(Save Excel spreadsheet as PDF. Bring PDF up in Mac Preview or some other PDF Viewer. Export PDF as JPG.)

 

Asteraceae Ray/Disc Color and UV Characterization

 

Notes: Asteraceae flower petals are called Rays. Asteraceae centers are called Discs. Some Asteraceae flowers have only rays and are marked "ray". Some have only disc florets and are marked "discoid". If there is a question mark on the chart, it means I couldn't figure out the entry just yet.

 

Right Ray or Right Disc Column: UV-signature.

I have not yet figured out the best descriptions for a flower's UV-signature considered as a whole. We do have some terminology already in use such as "central bull's-eye" or "uniformly UV-absorbing". But for this initial attempt, I have only listed whether a Ray or Disc is primarily UV-absorbing, primarily UV-reflective or has both. (These designations have only been made for the flowers in the [A-B] section of the chart.)

Here are the abbreviations:

• A = UV-absorbing
  
• R = UV-reflective
  
• AR = some of both on the ray or disc.
  

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Center Ray or Left Disc Column: Ray or Disc Color Sample

To determine a flower's ray or disc color I sampled the posted visible JPG with a color sampler large enough to average out an inclusion of lighter/darker areas on the ray or disc. I avoided shadows and spectral blowouts. The sampled color is labeled with its color wheel hue. If the ray or disc is multi-colored, then the first hue listed is the primary hue. If the ray or disc is white or just slightly off-white, then no color sample was taken on the JPG. If a flower has no rays, then you will see "na" for "not-applicable" in the center ray column. Similarly if a flower has only rays then you will see "na" in the left disc column.

 

No need to remind me of all the approximations which have gotten between my JPG color sample and an actual flower's color. I'm well aware of the potential flaws in this method of determining a flower's color. However, this method does seem to serve well enough for placing the flowers into generalized color groups.

 

Left Ray Column: Main Color Group

If a flower has only rays or has rays and a disc, then the color patch in this column represents the ray color. If a flower has only center disc florets and no rays, then the color patch in this column represents the disc color.

To characterize the sampled hues, I gave each one full saturation and brightness in order to better "see" it. The pure colors were patched into the left ray column. Then I divided up the color wheel and named the colors as seen in the next chart. The chart also includes some desaturated versions of the named colours many of which are common flower colors. The abbreviations were added to the pure color patches.

I was initially undecided whether to call the color (255, 0, 128) purple or violet. Eventually I went with purple so as not to confuse (255, 0, 128) with spectral violet.

 

Notes: Some Asteraceae flowers have only rays and are marked "ray". Some have only disc florets and are marked "discoid". If there is a question mark on the chart, it means I couldn't figure out the entry just yet.

 

None of this was as easy as I thought it was going to be!

 

Flower Color Groups

[Andrea B.]

The false colour patches in these charts are not sampled from UV photos.

Instead, the false colour patches represent 7 false color types for the largest false coloured areas on the petals of the flowers in the charts. Intensity of the false colours is characterized very broadly.

• black/white/grey
  
• dark blue & light blue, and
  
• yellow & dark yellow
  

Although we have attempted to standardize the representation of UV false colours in our botanical section by requesting that everyone white balance their UV photos against a known, UV-stable, white standard, false color results are still going to vary widely due to known factors discussed elsewhere. And in the field we never are able to get an even illumination of a flower at a fixed illumination intensity which would be required for there to be any kind of accuracy in charts like these.

 

It is particularly difficult to decide whether a flower is "moderately" UV-reflecting/absorbing because of the natural variation in photographic exposures.

 

The visible colour patches are also sampled broadly to obtain an average hue for a petal.

 

So, please take these charts as a simple but inadequate incomplete attempt to characterize our posted flowers. Any correlations taken from these charts would need to be verified with proper measurements using spectrometric equipment.

 

The Poppy Family

 

The Buttercup Family