Source : WordNet®

black cottonwood
     n 1: North American poplar with large rounded scalloped leaves
          and brownish bark and wood [syn: {swamp cottonwood}, {downy
          poplar}, {swamp poplar}, {Populus heterophylla}]
     2: cottonwood of western North America with dark green leaves
        shining above and rusty or silvery beneath [syn: {Western
        balsam poplar}, {Populus trichocarpa}]