Ok I have been making a game recently and took a little time out to try and brush up on my pixel art(no pun intended), as I have not seriously applied this ability in quite some time. I went through a few tutorials to refresh my knowledge of the basics(and learned a few new things :D), looked at a couple of samples of trees then gave a tree a go.
Here is the outcome:
It is by no means perfect, but is the best I could do(I have never had much of a talent for foliage), please tell me what you think and try to keep the criticism constructive.