Another lichen – or is that two?

The next lichen I wanted to try to ID is one that hangs off twigs like a pale green beard, with lots of thin wispy branches.  It originates from one point so it is a fruticose (bushy) lichen. 

The first question is about the cross section of the branches – round, flat or grooved. 

These look round which narrows it down to 4 species all which all have names starting with Usnea.

Unfortunately, after that it gets a bit tricky… the next distinguishing feature is to do with reproduction and asks if there are any "soredia".  Not a term I know, so looking it up they are powdery granules on the surface. Here's a close-up:

Well, I can see some little specks on the surface but is that what they mean?  Quite honestly, I don't know as I have not had any experience with lichens.  There is another lichen that I picked up that I thought might be an Usnea.  It's a bit darker but otherwise similar.

A close up of this one does show something on the surface:

So my best guess is that they are both Usnea  and might be Usnea cornuta or Usnea subfloridana, and I can't get much further than that! I notice that the British Lichen Society says don't try to ID Usnea to species, just record Usnea so I will have to be content with that.