Wolf lichen (Letharia vulpina)

[rjlittlefield]

Inspired by Ralf's beautiful sections of lichens, I decided to try my hand with one of our local species.

This is "wolf lichen" Letharia vulpina (ref, ref), from a specimen that has been sitting on a countertop since I collected it several months ago. It is quite dry at this point, but I think this is not an unusual state for this lichen since it likes to grow in full sun on bare branches and stumps in dry conifer forest.

This section is cut from a medium-sized branch, about 1.2 mm average diameter. You can see that the structure consists of an outer layer that is a uniform yellowish color, a middle layer that is an irregular distribution of green-colored algae, and a hollow core that consists of colorless strands of fungus. The yellow color is somewhat water soluble and I believe is the chemical compound(s) that used to be used for dye and poison.

I read that reproduction in this species is non-sexual, through soredia not shown here. I don't know what the two brown spots are.

--Rik

Technical: Canon SD700IS point-and-shoot through 10X eyepiece, 20X NA 0.4 achromat objective. Top lit using dual-fiber halogen illuminator, ping-pong ball diffuser. Stacked, minor CA removed with PTLens. Handcut dry using single-edged razor blade under dissecting scope.

[ralfwagner]

Very nice, Rik.

That ping-pong ball illumination does a great job with lichen sections. The colors appear very bright and natural. Some day I should install that illumination with my mic, too.

I always found it difficult to cut dry lichens. I use to put the dry ones into water for some 10 - 30 minutes and then cut the wet ones in a drop of water. An other method is the use of PEG as a stabilisator. I have described this PEG method earlier in this forum: http://www.photomacrography.net/forum/v ... php?t=3671

You have indeed a very good area for lichens there at the west coast! In my area this Letharia vulpina is very seldom, as is the lung lichen.

[rjlittlefield]

Thanks, Ralf.

I had trouble cutting these lichens dry when I tried first -- they kind of crushed and crumpled. Then I tried soaking them in water, but they got too soft and with the hollow centers they deformed too much to get good slices. So I went back to dry, but using a completely new blade, and was surprised to find that it worked great -- nice uniform slices with very little deformation. This is my first experience with these things, so I have no idea what will happen with other kinds or even different pieces of this one.

--Rik

[Ken Ramos]

Wolf Lichens I thought only I went around handling stuff like that. I don't suppose I will ever run across anything like those out here but there are a few questionable things I come across from time to time. Really a nice photograph here Rik , I envy you guys with the microtomes. Maybe one day I will break down and purchase a nice one that I have been "goon'n" over.

[rjlittlefield]

I envy you guys with the microtomes.

I know, you're joking, but I just had to check. Turns out, this section is right at 100 microns thick. (I left it uncovered, so it deformed a bit, but still it fit within the 150 microns range of my scope's fine focus knob.) Quite a bit thicker than standard microtomes, for which Wikipedia says 2 to 25 microns.

One reason for the top lighting is that the section is so thick it's very dark with backlight.

--Rik

[Ken Ramos]

Okay, well you did a pretty good job "freehanding" the section then. I tried to do a few sections once, here a while back, with a homemade rig that produced less than modest results. Of course my subjects were not the best...woody stems.