Collema, a jelly lichen

ralfwagner · Post by **ralfwagner** » Sun Oct 21, 2007 8:24 am

Hello,

jelly lichens are with cyanobacteria as their photosynthetic partners and they are gelatinous when wet and brittle when dry. Here I like to show my first finding of a jelly lichen, some Collema spec. . In contrast to most other lichens the hyphae are distributed over the whole thallus and there is no differentiation between top and bottom in the leafs.

a) Leaf with isidiae

b) Thallus-section showing the cyanobacteria and between them the fungus

c) Thallus-section

BJ · Post by BJ » Mon Oct 22, 2007 2:41 am

Ralf,

Great photos. I am intrigued to know how you made the sections? I have found it very difficult to do simple sections (without a microtome) with Collema and Nostoc because they are so gelatinous. i usually just give up and do a squash.

Thanks for the photos

Brian

ralfwagner · Post by **ralfwagner** » Mon Oct 22, 2007 11:53 am

Brian,

I know this problem with lichens, mosses and also nostoc. I found it difficult to cut them in a hand-microtome and so I cut them now without. Just with a razor blade in my right hand and the lichen (immersed in drop of water) pressed to a slide with my left forefinger. The forefinger is used also as a "guideway" for the blade. All this is carried out under the stereomicroscope, 5x to 10x magnification. You might call it quick and dirty, but it works fine for me. Sometimes, e. g. with small mosses, it is useful to put the moss on a slide, immerse it in a drop of a 20 % solution of PEG 1500 (Polyethylenglycol, Histowax), and wait until all the water is evaporated. The PEG 1500 fixes the moss ancillary on the slide. Then the sections are put in water and the remainig PEG 1500 will be completely dissolved by the water.

BJ · Post by BJ » Tue Oct 23, 2007 2:59 am

Ralf,

I was afraid that you would give that answer. Basically it comes down to skill and patience..... two attributes which you obviously have in abundance and I lack !!

Thanks for the tip about using PEG, I can see how this would help with some subjects that are difficult to section.

Keep looking down.

Brian

rjlittlefield · Post by **rjlittlefield** » Tue Oct 23, 2007 5:59 am

Ralf,

The cross sections are great.

In the first picture, I'm curious about the bright green moss-like structures. What are they, and what is their relationship to the jelly lichen?

--Rik

ralfwagner · Post by **ralfwagner** » Tue Oct 23, 2007 10:50 am

rjlittlefield wrote:
In the first picture, I'm curious about the bright green moss-like structures. What are they, and what is their relationship to the jelly lichen?

--Rik

Rik,

nothing special with that. These structures are just mosses, that grow together with the lichen at the same place. There is no relationship between the lichen and the moss, just neighborhood.