I have heen studying traditional pen and ink illustration and sribble line art.

One way to approximate this easily is to use the Roughen Live Path Effect.

The graphics below show some examples. Most of them are done witb only a stroke setting of 1 pixel. You can increase this to whatever suits you and try many different shapes,

To me, you can achieve shrubbery like results and good starting points for other things.

Have fun and create great art today.