I made them because I thought it was odd that there weren't really any big trees.
Right now, the supercontinent would be where forests are generally darkest (black-pigmented shade trees), followed by Drake (trees dense but reflected green light gets down easily), then Maineiac (nothing was suited to become a shade tree, much more light reaches the ground), then Hydro and Barlowe (largest trees are palm-like, very sunlit forest floors).