Fast growing trees and hedges for zone 7a?

[csziggy]

1. Sycamores are the fastest growing tree I know

But the leaves are a pain - though I have to say, at my old house site that was surrounded by sycamores we never had a weed problem since the leaves made great mulch. I like the sycamores since they are deciduous so you get sun in the winter and shade in the summer. http://davesgarden.com/guides/articles/view/887

Tulip poplars grow pretty fast, are deciduous and have pretty flowers. http://davesgarden.com/guides/articles/view/3765

Both sycamores and tulip poplars get very large so might overgrow your yard. But if you are only panning for the next 20 years, they probably won't be a problem for you.

Do NOT get a silver maple - while they are pretty, they are brittle and tend to break off branches when they get big enough to provide shade.

http://davesgarden.com/guides/articles/choosing-a-tree-for-your-yard

How tall do you want the hedge? We had anise bushes that are evergreen and in ten years got to 20+ feet. They look something like ligustrum but are a lighter green and are not as invasive as ligustrum. (Plus I don't react to anise blooms the way I do to ligustrum.) The anise seeds are NOT the star anise you pay for in the spice aisle. http://davesgarden.com/guides/articles/view/2759/