I would go for dubsivision surfaces.
Make for example a sphere or a cube, hit subdivision and start extruding polygons.
Another way to do it is to simply draw a curve and extrude a circle along this curve. I dont think this would produce a very good result as the thickness of the rootsystem would be all the same, but I guess you can fix some of that by applying a displacementmap to the geometry.
Hope this helps