Rio Grande cottonwood, álamillo

Populus fremontii S. Watson var. wislizeni S. Watson, Amer. J. Sci. Arts, ser. 3, 15: 136. 1878 (as fremonti); P. wislizeni (S. Watson) Sargent

Plants to 35 m, usually less than 20 m. Winter buds pubescent, hairs relatively short, stiff. Leaves: blade base with 0 basilaminar glands, apex short-acuminate, abaxial surface glabrous at emergence; preformed blade with (3-)5-10 teeth on each side; neoformed blade lengths usually less than widths. Pedicels: lengths uniform, (5-)8-12(-15 in fruit) mm. Capsules with thick, stiff valves.

Flowering Mar-May; fruiting May-Jul. Floodplains, permanent streams, near springs, usually in moist soil, often planted near ranches, irrigation ditches, in towns; 1000-2300 m; Ariz., Colo., N.Mex., Tex., Utah, Wyo.; Mexico (Chihuahua).

Subspecies wislizeni is the common cottonwood of the Rio Grande and Colorado Plateau regions, where it forms relatively small, scattered groves. It is a fairly homogeneous and distinctive southwestern part of the species. It intergrades with subsp. monilifera on the eastern and northern margins of its range. Populus sargentii Dode var. texana Correll is based upon such intergrades.