A.p. 'Green Elf' is an unusual dwarf, and should make a lovely patio tree. As it is described by the grower: "The rounded, serrated leaves are not very elfish. They are, in fact, large for a dwarf tree. But they are green, initially a yellow-green then a dark, rich, handsome hue. Fall color varies from yellow to gold. This small cultivar can reach 5' in 10 years and may mature at 6'. Green Elf can handle full hot sun to nearly full shade." The samaras are also quite nice, as are the vivid crimson leaf stems, IMHO.