Splitting Open A Node

Inside a swelling the growth was layered. I could not tell much more without a microscope.

No pigments other than some green, and I wonder if the puffy tissue is infected by symbiotic microbes..?

These ones are the ones I'm guessing might have made it into the roots, and flowed up the stem, lodging here to grow:

http://www.advancednutrients.com/advancepedia/product.php?productID=63&catID=18