One of the most common criticisms of X-Plane 10‘s default world is that it is all the same. The rolling fields and grasslands have very little to look at when flying VFR at low level, which isn’t particularly like the real world, to be honest.

Tree Lines and Farms, by alpilotx.net is a free add-on which not-entirely-randomly adds farms and treelines to break up the basic scenery. If you visit the developer’s page, you’ll see some of the technical methodology that goes into how it adds what it does and even a description of some of the slight errors made during initial development and testing. You can also download both versions of the add-on, one for Europe and one for the USA.