This variable species ranges widely across temperate regions of North America, but typical deltoides is restricted to the eastern half (Ch, FNA 7). Leaf size tends to be larger in native trees of southeastern states. Much deltoides is grown for pulp-production on lowlands of the Mississippi Rv. in Ky. by the Weyerhaeuser Company. These trees are derived from clonal propagation of selected or engineered germplasm. Included here as open dots are the unverified historical data of Gm and B. Although widely scattered over Ky., deltoides mostly occurs along larger rivers with much fresh alluvium deposited each year. Its small wind-blown seeds have allowed local establishment in modern cleared landscapes. But deltoides was much less common in 1900-1910, when it formed a significant component of timber resources only on lowlands of the Shawnee Hills, and along the lower Ohio Rv. and the Mississippi Rv. (Gm, Barton 1919). Hybrids with nigra have been cultivated widely across eastern states (K, W), but escapes are unknown in Ky. Leaves of deltoides and several other species in the genus (sections Aegeiros and Populus) flutter distinctly in the wind, more so than any other North American trees. This behavior may have functional significance for resisting damage from wind, dispersal of light within the canopy, enhanced diffusion of volatile phytochemicals, reduced temperature of more exposed leaves, and reduction of herbivorous insects (Vogel 2009, Roden 2003, Yamazaki 2011, Warren 2015).