The first and simplest way I draw common trees, the cross section approach, as seen in the Jungle Stream.
In this mini-series I explain my three methods of drawing trees. Each has its own place and purpose, this one being ideal for tightly-packed forests where the canopy would otherwise cover your map!
This video features the Jungle Stream and Icy battle Site maps.
Looking for the other parts to drawing trees? You can find them below: