New species of alcohol-preserved micro-orchids

[Lou Jost]

These little orchids are why I got interested in extreme macro. They range form 2mm to about 15mm. I discovered many of them 15 years ago in remote Andean cloud forests, and I preserved their flowers in alcohol. They lose all color and become translucent, very hard to photograph. Here is one of the species I am currently describing, in the genus Teagueia. Note the bright "crystals" embedded near the margins of the flower parts.



A closer view of the petals, with oblique light:



A backlit view showing that the "crystals" are actually opaque:



This is what it looked like when I collected it 15 years ago (I scanned the old negative on my Nikon Coolscan 5000):



When publishing a new species, it is usual to include a botanical drawing of it. I use my photos as references for these drawings. Here is my drawing of this species:

[zzffnn]

Great work, Lou.

Those orchids are very beautiful!

How did you image photos #1, #2 and #3, especially #2 and #3? On bellow/rail, or microscope? What magnification and objective NA? Thank you for sharing!

[JH]

Nice photos and drawing.

How did you do the first picture. I always find alcohol difficult because it evaporates so quickly.

Best regards Jörgen

[Lou Jost]

The big one is a reversed 60mm Micro-Nikkor D (with focus set at conjugate m) on a D90 and a Stackshot rail. The higher-mag pictures are again D90 with Mitu 10x on an ancient Nikkor-Q 200mm tube lens.

That was last year though. Now I can do this much faster and better using my Oly PEN F. The publications where these orchids will appear have tight deadlines and I have a lot of species to describe, so workflow speed becomes important. I have a cheap stereo microscrope whose head comes off. So I set up the dissection under the scope, then lift out the scope and lay the PEN F + Oly 60mm right on the ring that used to hold the stereo head. I have an L-bracket permanently mounted to the camera and this sits flat on the ring that used to hold the head. I use in-camera focus bracketing and Ikea lights, and it does a stack in less than a minute, as opposed to half an hour using flash and a rail.

Here is the result (same flower species, but less care in lighting, and pollen not so pretty as the last one). Stack made from jpgs straight out of the camera, and no post-processing (no sharpening or level adjustments):



The resolution is pretty good, as you can see in this 100% crop, which would be sharper if I adjusted it:

[Lou Jost]

Jorgen, sometimes I slowly add water to it, then replace in alcohol when I am done. But see the note I just added; for pictures up to about 2x, in-camera focus bracketing is so fast that this is no longer an issue. (For m>1x I use my home-made auto-extension tube to control the reversed lens' focusing and aperture.)

[MarkSturtevant]

Very good! That last one may make the journal cover.
Wondering about the crystals. Could they be formed as a precipitate from something that was insoluble in alcohol?

[Lou Jost]

Mark, those crystals are widespread in this subtribe of orchids, and they are made of a calcium compound. Your question is a good one, I should see if they are the same color and texture in the live flower, though the pigment masks them.

[rjlittlefield]

A backlit view showing that the "crystals" are actually opaque:

I expect they're translucent and highly diffusive, like heavily etched glass. When backlit, that would look dark because of scattering light in all directions, most of which are away from the lens. But when side-lit, it would look bright because of scattering light in all directions including toward the lens.

I use my photos as references for these drawings. Here is my drawing of this species

The drawings are excellent -- you're very good with pen and paper as well as lens and sensor.

--Rik

[Lou Jost]

Thanks Rik!

We'll soon have electron microscope imagery of these flowers, and the crystals will be interesting to see.

[zzffnn]

.....and they are made of a calcium compound.......

Are they made of calcium oxalate, which is a common product of plant metabolism? Like those in onion or garlic skin?

[mawyatt]

Lou,

Great work!! I really like your hand sketches too, very artistic.

Well done sir!!

Best,

Mike

[Lou Jost]

Fan, yes, these are calcium oxylate crystals.

Mike, thanks very much!

[MarkSturtevant]

So according to my wife, who is a bit of a botanist, calcium oxalate crystals can be used as a feeding deterrent.

Fan, yes, these are calcium oxylate crystals.

[Lou Jost]

There is a form of calcium oxylate that is needle-shaped, and these are called "raphides", which deter feeding. But the ones in my flowers are blunt, and I don't know if they would have the same effect.

[Beatsy]

This is a great set of pics Lou and a very interesting project too. I rather like the lighting on the "less care" one, particularly in the bottom half of the pic. Gives it a real sense of depth.