I second this question! My wild guess is that the high poly branches (one with and one without leafs) and a bunch of individual leaf variations were created and baked in maya/, then the low poly branches were created for LOD0 (individual leaf cards on top of a plane with baked bare branch) and LOD1 (same as lod0 but without individual leafs cards), and then everything was put together in Speedtree since the materials use its nodes for wind, but would love to know for sure.
If they did use Speedtree it’d be to know more about it, whenever I try it I just end up with ugly random branch / leaf placement, never looks as good as placing everything by hand 