It is some variety of Japanese maple. Did you find it as a seedling? If so, it is possible that it has a weeping form in its parentage. It could also just not be mature enough to support itself yet - the trunk looks very skinny for the size. I'd give it more time to mature. And you want to make sure the attachments to the staking allow the tree to flex and move with the wind (while still providing necessary support). It is this flexing/movement that helps to develop the trunk properly.

FWIW, if found as a seedling and not purchased as a named, grafted selection, it is just a red leafed Japanese maple - no cultivar assigned.

Thanks. Yes I did find it growing as a seedling. The trunk is small for it's size. About and inch at it's base. Is this normal for some varieties of Japanese maples?

the branches do look like a weeping variety. those upper branches are very large for the tree's trunk to support.

how you like the tree to look? upright, bushy, mound, etc?

how tall do you want it to be? a large shade tree, or small, medium ornamental?

Yes, many young Japanese maples, especially seedling forms, grow faster than you might expect and become topheavy, with the upper growth not fully supported by the slender trunk. It's pretty much just a matter of having patience :-) Eventually the trunk will thicken.

I'd be quite careful about pruning at this very young age. You may wish to remove one of the very long top branches but I'd be inclined to leave everything alone at this point....the tree is growing well, just still very immature.

I would not hesitate to prune a tree as out of shape as this one is. Waiting to prune means the tree will be even more mis-shapen as it grows. You must intervene early if you want the tree to have a proper form. 5 years old is plenty old enough to prune. Maples respond well to pruning, and I've pruned at all times of the year with great success.

An example of a neat tree plucked up for free! Everyone should see this. Not sure what to do about all the top heaviness. Just make sure you aren't damaging the trunk with the supports which I think its pretty obvious are necessary.

Is the tree fertilized? Excess of high nitrogen fertilizer can give a Japanese maple a floppy, top-heavy growth habit like that.

I think we may have some differing opinions :-) I am not at all convinced that this little tree is "out of shape" - it looks pretty much like a young, immature seedling maple should. And I'd wonder what exactly would be contemplated with regards to pruning to get it into "shape". JM's typically require minimal structural pruning and with young trees, the branch structure does help to develop the trunk.

Since all the branching is still very small diameter, I'd be inclined to give it another season or two and then reconsider any pruning needs. Growth is often the most rapid with young trees and will slow as they age.......it is my opinion that like a gangly teenager, this tree just needs to grow into itself. And I'd also agree that any fertilizing is not necessary.

Thanks for all the replies. I think I will let it go for a couple of more seasons and see what happens. There's not much to prune anyways. It's hard to tell from the photo but most of the upper branches are really short so I don't think cutting some of them would make too much of a difference. Also I don't fertilize it. Here's what it looked like when I planted it.