I use dried parsley flakes, and paint them. For variation I will use other dried herbs, and birch tree seeds ~ the herbs must be painted over time they will turn color.
I start my trees or thick hedges with sage brush bases (for variation I will use dried roots) to start with. Depending on the need, trees or shrubs I will use seafoam (or dried flowers) or scouring pads for the smaller branches. I have used super glue, or white glue.
Method 1. With the sage brush or dried roots as the base, I will drill little holes to place more seafoam branches.
Method 2. With the scouring pad, I will pull it apart until it is thinned well, looking more like branches. I usually will base coat the scouring pad with paint before I glue it to the base. I will place drops of glue (super glue) here and there to fix it to the sage brush base. I will trim and shape the scouring pad until I get a shape I am happy with. At this point I will go back and touch up the paint. These are the basics for most of my trees and shrubs. To flock with the herbs, I will use a generous blast of spray mount and sprinkle on the herbs, step and repeat if needs be. Airbrush the color I want and call it good.
Hope this helps...
Here is a couple of photo's of stuff I use...

