More Manzanita Markings

Continuing to make my way through photos I took in northern California last October, I just came across these shots of the trunk of a gnarled old manzanita (Arctostaphylos).  The remaining bark looks as if someone poured melted red wax down the stem.

I’m not sure what happened to it to make it look like this, although looking at it now, I see lots of old horizontal grooves in the wood, and presumably that was the injury that killed the bark.  I wonder if that has anything to do with this?

It also occurs to me now that similar horizontal markings sometimes appear on mountain laurel (Kalmia latifolia), another member of the heath family (Ericaceae) and the most manzanita-like plant that grows in the eastern US (although bearberry, a plant that grows low to the ground, is actually in the same genus: Arctostaphylos uva-ursi).  Coincidence?There are examples of these markings on BugGuide here.