Why is the poem "Yggdrasil" placed where it is in House of Leaves, and which narrator included it?

Question

At the very end of House of Leaves, there's a page:

The word "Yggdrasil" doesn't appear anywhere else in the book, and the index, which amusingly lists every word in the book and where it shows up (including some that don't), confirms this.

I've got a lot of questions about this poem.

1. Why does Danielewski bring this poem in quite suddenly on the last page of the book, without any clear callbacks to any other references in the book? As far as I'm aware, the notion of a world tree doesn't appear anywhere else, and the book doesn't contain clear allusions to Norse mythology as a whole.
2. Which narrator in House of Leaves are we supposed to interpret as the one who decided to include this page? Is there anything to suggest which one of them it should be?
3. The poem is supposed to be interpreted as physically looking like the worldtree itself: the "Ygg" and dot at the top are the canopy, "d/r/a/s/i/l" makes the trunk, the poem forms the base. But... what is the large "O" supposed to mean at the bottom of the poem?

Answer 1

Yggdrasil is an Ash Tree that splits into every known reality, and the house is on Ash Tree Lane, so it does actually have a pretty constant and repeated reference throughout the book.

Answer 2

The World Ash Tree of Norse mythology translates to "Odin's Steed". "Ygg" in turn translates to "terrible one". Odin hung himself for nine days on the tree in order to acquire knowledge of the runic alphabet. You can read more about it here.

This echoes Navidson descending into the House to tackle his personal demons, which echos Truant descending into Zampano's work to tackle his personal demons. And of course, once you realize what Yggdrasil is, it becomes apparent that it can literally be described as a House of Leaves.

But I find it odd that people assume the "Ygg" is the canopy and the poem its base. It feels like such a stretch. Next time you get the chance, go to this page and flip the book upside down. What do you immediately see? What the poem tells you that you should see: "Its roots must hold the sky."

But how can a tree's roots hold the sky? Why would it be upside down? Well, if you've ever been by a lake, you've seen plenty of trees whose roots hold the sky: the reflections. Reflections are just the visual form of an echo, and echoes are a running theme in HoL.

O
Its roots must hold the sky.
But doesn't reach the ground. Still it stands.
It stands ten thousand feet high
What miracle is this? This giant tree.
Yggdrasil
.

Answer 3

There is a chance the reference to the world tree could be a hint towards an interdimensional theme of sorts. I know it seems quite corny and not in the spirit of the book, but The House being a gateway of sorts and having characters hop between parallel versions of themselves clears some things up, such as how Zapano can be both blind and able to watch films, and why some people seem to remember the Navidson Record while others don't.

Answer 4

I would argue that it's one final self-referencing theory about the house. Perhaps the house is part of Yggdrasil. One single root network connected by unknown means to a vast body of incomprehensible size.