A couple of very young Gum trees, (photo 1), possibly Swamp Mahogany??? Quite thick bark comprised of layers of ‘sheets’, a bit like a paperbark but tougher, and with a lot of vertical splits in the layers, which also seem interlaced with an almost stringy textured bark (photo 2 and, especially, 3). Leaves are thin but leathery, (photos 4 & 5, with the latter showing some underside aspect).