Duckweed in UV

[Andrea B.]

holy wow!

All this fascinating gear!!

 

Birna, your macro photos are so amazing.

[Andrea B.]

With reference to a previous comment by Clark, how are these little-bitty duckweeds pollinated? Water insects perhaps? Self-pollination by water motion?

[nfoto]

A good question, Andrea. The anthers (two pollen sacs to each stamen) quite violently dehisce when they are in contact with water, thus I suspect rain, or wind-induced movement, would make the pollen grains fly everywhere. The ovules just sit there patiently waiting to have pollen deposited into their upward-pointing "stigmatic" surface which is strongly funnel-shaped (I hesitate to apply the term 'stigma' as the structures are so reduced thus hard to say what they are the equivalent of).

 

I often see pistillate flowers with deposited pollen grains. However, the plants probably are self-sterile and large populations might just be originating from one or a few clones. Thus, seed set is apparently more rare than flowering itself. There is some morphological and molecular genetics data suggesting speciation in this genus might be driven by hybridisation. Thus, Lemna japonica is believed to have arisen from a cross between L. minor and L. turionifera. In fact, L. japonica has morphological features from both of the putative parents so its appearance is consistent with molecular data for once.

 

In some regions, the Duckweed-dominated floating-plant community can comprise several genera and more than one species from each as well. I once counted 7 different duckweeds on a single photo from a Dutch canal.

[SteveE]

I do not know any american company that are selling this types of profiles and components.

 

You can find them on Amazon or eBay by searching for "T slot", "T-Slot", or "T-Slot Extrusion"

They are widely used for building 3D printers, which require similar sturdiness

[Andrea B.]

That is a fascinating analysis of the duckweed pollination possibilities. Plant life is every bit as complex as animal life, isn't it?

 

It makes sense that cloning plants would maintain an alternate reproduction strategy for long-term survival. In case there was some dramatic climate upheaval (heh-heh....) or other disastrous change, there would be a few duckweedies floating around with a slightly different genetic mix which might survive.

[Lou Jost]

What great pictures! I'm new here and keep finding amazing things like this.

 

One thing caught my eye about the setup of the UV 105 + reversed lens. It looks as though the 105mm lens is fully extended.  This doesn't seem ideal; normally the best optical quality is obtained when the tube lens is focused at infinity, as you did with the Raynox. Was there some advantage to extending it?

[nfoto]

Extension added to alleviate vignetting and spherical aberration. Do note the reversed lens, in that case a Noflexar 35/3.5, is not directly comparable to the usual long-distance objectives like the Mitotoyo range and it is tricky to get the pupils of the two components to match so that vignetting is eliminated.

[Lou Jost]

Good reason.

[Andy Perrin]

19 hours ago, Lou Jost said:

Good reason.

This is characteristic of a lot of situations in UV photography, where the "usual rules" of visible light photography are superseded by the constraints that are forced on us by working with equipment outside its usual design range. A simpler example would be lens "speed" being determined primarily by UV transmission and only secondarily by the F/number.

[Lou Jost]

Yes, and that is true of extreme macro photography in general. This vignetting problem (and its solution) is common with coupled lenses, regardless of wavelength.