Baiera

Baiera was a tree of the family that contains the modern Ginkgo. It's a leaf genus, assigned solely by the morphology of those structures, so it was probably a diverse group. Its longevity sure seems to suggest that; Baiera came to be in the Permian and died out halfway through the Cretaceous. That makes this tree very suitable for your dinosaurs pretty much everywhere as long as it isn't too dry. Update 16: updated with the new 'parent group structure' mechanic. Disband it to separate the plants. The individual plants are still aligned to the ground properly, but the prefab as a whole isn't.