The texturing was just a matter of picking & prodding with dental tools.  Giving the whole tree a little 'twist' gave some of the carved straight lines an interesting shape.  After getting the first foliage cluster attached, I figured I had better finish the base or I wouldn't be able to get to it.  The root system and lowest part of the trunk are made from Milliput.  I didn't figure the paint and foliage would go through the oven very well so I had to opt for an epoxy option.  

Here is another pre-foliage trunk photo:


And one showing the top branches poking through...


There are more WIP photos added and prefixed with 'smallIMG' here:  http://ryan.skow.org/trees/willow/wip