Shrub or tree? what will determine???

Excuse my extreme lack of knowledge here, i've only just started taking an interest in gardening.

I'm after a Japanese acer, and i undersand they can come in the form of trees or large shrubs.....

The ones i've seen in the garden centre are maybe 2 foot tall, but how do i know if they will be trees or large shrub?  Is it all down to how i prune them or is it genetical?

I'm hoping to have a tree with eventually a few feet of trunk etc

Some of the acers in the garden centre are single stem and some have 2 coming from the soil.  Is this what will determin trees and large shrubs?

Again, excuse my gardening ignorance and lack of knowledge 

I would say if it is a single stem it will grow into a tree and if it has a few stems it will grow into a shrub

In my garden I have an Amelanchier tree and also an Amelanchier shrub

Choose whichever suits the purpose for your garden

Pam LL x 

The label should give you an idea of size and spread, If it's a good GC then there should be someone to ask as well.

You could look up the varieties in the Garden Centre on Google or a good gardening book, but generally if it has one stem - the future trunk - it will be a tree, or several branching stems from the bottom it will be a shrub. But there are many varieties.

Look at its shape and look at the label.  Generally speaking if it's growing low and hummocky it will stay that way but may reach quite a large spread and a bit more height over time.

More upright forms will get taller.  Sango Kaku is a good small tree with bright red stems in winter.  Mine started out about 4 or 5' tall and is now well over 2 m high though its stem ends get frosted every winter here so it may grow taller and faster for you..

Thanks for your help guys, i've got a better idea what i'm looking for now