How do I make Trees for walls?

I want to make a tree or grouping of trees to be used as a wall in a twin stick shooter type game. Ideally I would have a single tree used as a tile background + solid behavior. Doing it this way lets me have a repeatable tree I can use for different size walls except it doesn't look very good because its just a line of single trees with a lot of space between them.

I did some searching and couldn't really find what I was looking for so any suggestions? I can do groupings of trees that repeat but that gives me either gaps in between tiles or cut off trees on the ends of the wall. Trying to keep the number of sprites and art needed to a minimum.

I would be inclined to get a half dozen tree sprites and stick them together in a semirandom fashion, breaking it up anywhere I see monotony. This uses up a bunch of spirtes, but unless you are taking up an inordinate amount of memory, or spending lots of CPU time on your slowest target platform checking for collisions, it doesn't matter.

One alternative is a 9Patch. You can tile the inside, so trees overlap in an organic way, but the outside can be nonoverlapping with correct transparency. One of the difficulties there is that you can't rotate it without rotating the entire layer, but that isn't always a huge problem.

The first option I had thought of before but wanted to have more flexibility without having to make a new sprite for each size because I am using a lot of smaller layouts as rooms. 9Patch looks like it may give me what I am trying to do. I would like to be able to tile the inside section of the 9Patch image letting the outside sections overlap but that might look bad too. I will play with it a bit to see if I can make that work.

Thanks very much for the suggestion not sure how I overlooked 9patch I thought I read through the whole manual.

It lets you tile the inside or the edges, so one limitation is going to be that your size needs to be a multiple of the tile size so the inside lines up with the edges and corners.