Remix of Tree Generator Example from Geometry Nodes from Scratch - Blender Studio that uses a curve to generate the spine of a tree.  These trees grow in a +Z direction, so if your making top heavy trees reverse your curve! (Unless your into that kind of thing)

As of Blender 3.4, applying modifiers causes instance geometry to disappear, thus this modifier produces no instance geometry by default.  If you don't need to apply this Blender modifier, feel free to mute all Realize Geometry nodes in the Geometry Nodes group for improved performance.

Branch layers under the top layer have their tops trimmed so the tree can be bent more without producing weird artifacts.  If you don't need to bend your trees, feel free to set Under Layer Trim Factor to 0.