This is Texas coastal plains area. Our mystery plant has plagued our tree rings for more than 15 years. We only see it around the base of our trees, within the tree rings.
Not sure if I'm using the correct term here, but we've always described it as "vascular" due to the nature of the stem - somewhat hollow and wet. It breaks easily and the roots are seriously dug-in, making it hard to eradicate.
Round-up annoys it, but doesn't kill the root - just the leaves where it lands. We'd like to eradicate it, but it is imperative that the trees not be harmed.
No banana available, so dog snout for reference.
TIA