Oh I remember these trees indeed, but none of the roots are in comparison to the size of the Matron's Lethe. A general rule for most trees is that the roots grow out 2-3x the length of the branches/crown size, now we don't know where the root ends or where it begins but it's really big. Course SE could have just added this to be a cute infrastructure thing, but it's why we have the Lore section to ask questions...I still see the Matron's Lethe as being larger than those example trees.