What I do for my tree models is create the 3d model of the stump/branches, and then take a plane mesh, apply a branch texture, typically with leaves on it (can be found online or made with hi-poly modeling) and position copies of those planes around on the tree. Then, in UE4, I un-tick tangeant space normals in the branch material (I use blender which doesn’t support custom normals) and plug a constant 3vector into the normal spot in the material, with it set to 0,0,1
The material settings are so that the individual planes don’t have dark backfaces, and so that they all shade as a unit, rather than as individuals, so to speak.