Tree W.I.P
 

Here is a tree I've been playing with for a few hours, I just now am getting to the leaves :p
http://img108.imageshack.us/img108/7637/treeom4.th.png

i like it, but the contrast could be a bit greater

the trunk should not have brighter highlights then the tree top also the lines on the trunk are too uniform and need to be broken up a little if you define leaves and use shadows on the top along with the other things I mentioned it could turn out to be one badass tree

I just have aproblem with lineart, I think the trunk becomes too small for the roots that you made, you can change it by expanding the mid/upper trunk area and adding more leaves. There si actually a pretty abdass tutorial on trees at:http://petesqbsite.com/sections/tuto...o/chapter5.htm

If you are interested. (I mean from your work it kind of looks like you know what you are doing).

It really depends on what type of tree you're talking about and the age of that particular tree. That is what determines the width of the roots.