Isidia and Maculae

Once getting back from the field there is a lot work yet to do. Today’s post will be about one of the lichens that I collected and processed.

We had just gone over to this little creek off the horse trail. Beautiful, eh!

And while Jeanne was checking out the mosses I took a moment to look at a lichen. So it was on a dead juniper branch. I mean wouldn’t these colors make you want to look further? Me too! However what really got my juices flowing was the bumpy looking center of the lichen. I was pretty sure it was a shield lichen in the genus Punctelia. This group is pretty distinctive with the gray blue-green color and the white dots. Additionally this one had the bumpy center that was kinda yellow-green.
So I only found a couple of apothecia which is the brown thing. This is the fruiting body of some lichens. However as I said it was the bumpy stuff that got me excited!
Back at home with the specimen it was time to figure it out. In the field I wetted it to remove it from the small branch. It kept trying to go back to its original shape around the branch. So we flattened it. Here it is dry.
Spritzing it with water maybe now you can see the white dots better on the left and top. Isn’t that color awesome!

In this photo you can see the squarish lobes and the bumps.
A closer look at the bumps. These are the isidia. Each isidium is tiny out growth of the thallus. Think of the thallus as the skin to include the top layer and algae layer. Furthermore each one has its algal partner just like the main thallus of the lichen. So an isidium can easily be broken off to serve as a vegetative reproductive unit.
Under the dissecting scope I found some that had broken off.

Another nice surprise (for me) was a part called a maculae. This is a white spot on the cortex (upper skin of a lichen or top layer as I mentioned above) that does not have algae under it. All the algae is evident by the green color of cortex. Go back to my post Lichen, food for thought for a look at the parts of lichen.

So by now you are wondering what was its name. Did I figure it out? In fact I did this time. This is definitely not always the case. The chemical tests were done as well to confirm my ID. Furthermore it was the C (bleach) test that clinched the ID with a really really quick red reaction. Oh you want the name now…

the Rough Speckled Shield Lichen or Punctelia rudecta!

One more thing…Kathy (Hill Country) reported she had her first scissortail yesterday and Susan (Wise County) had FOS Ruby-throated hummer today! Yippee!

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Keep looking!

The more you know, the more you see and the more you see, the more you know


  1. I’m completely lost with the lichens but enjoyed the articles. Yes very pretty picture of the moss covered creek bank.

  2. The food for thought lichen posts wonderfully fun! I had forgotten it. Perfect reminder of all the details. Did you eat the peanut buttercup and chocolate?

  3. Nice article about climate impacts of gardening. I’ve been looking into alternatives to peat moss like coconut coir (a by product of coconut as food) since we use 1-2 bags of soil a year starting seeds.

    Beautiful lichen!!

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