I have a tree (or weed or some kind of plant) growing out back of my
house. I've only seen one other like it in my life, and that was about
20 years ago, so they are either very uncommon or they are constantly
cut back by homeowners (although I've NEVER seen one in the woods).

Basically it has a single stem or trunk, although there are a couple
of minor offshoots coming off the base.

In its first few weeks in June, it grew roughly 6" per DAY! In the
last month it has only grown another foot and now stands about 15'.
What is more remarkable here is that its root structure HAS to be
horizontal: it is growing out from under a pile of roofing shingles
and tree branches that I discarded on a concrete slab.

The main stem/trunk is about 2" in diameter, woody at the base but
quickly becoming green about a foot or 2 up from the bottom.
About every foot or so are 3 "branches" radiating from the trunk at
roughly 120 degrees. These "branches" each terminate in a single leaf.
The leaf has a shape something like gum, but the lobes are not as
pronounced. The leaf is fuzzy on the bottom side, and the top tends
toward shininess although it also has a slight fuzz. It's pea green on
top and lighter on the bottom.

Now here is the clue that makes this tree unique: most of its leaves
are in excess of 20" across!

Now, you'd think that I could come up with something real quick on
the net to identify this critter with no problem. WRONG!
Almost every damned "plant identification" site is nothing but a
bunch of pictures. I guess you're supposed to look at them until you
see something that you can say "Hey! That's the one!" to. I couldn't
find one single site in which you could taxonomically zero in on an
ID. Is there such a place?

Anyway, I thought I'd try and see if I would have any luck here.