Matron's Lethe

[Andaeron]

Oh, you're right- it IS a root. Maybe the name actually refers to the giant pit at the top?

Nope, I just checked. The name only pops up when you are ON it, not under. Also, the marker is much farther east than the hole at the top.

According to the Wiki page for the River Lethe, the word in Classical Greek literally means "oblivion", "forgetfulness", or "concealment". Not speaking Classical Greek and taking their word for it, maybe it comes from that last meaning, though I found no source that lists that as the meaning of the English word.