Populus deltoides ssp. wislizeni
Common: Narrowleaf, Alamo, Guerigo
Wyoming, Utah, Arizona, New Mexico, Colorado, Texas, and Oklahoma
A deciduous poplar of the Willow family, the Rio Grande Cottonwood has a broad, flattened, open crown of large, widely spreading branches. It grows to 40-80 feet. Its trunk has a diameter of 2-5 feet. It is a fast-growing shade tree and prefers wet soil along streams, grasslands, woodlands, or near lakes in deserts. On young trees, the bark is thin and gray-brown. On older trees, the bark is reddish brown and furrowed. The leaves are somewhat triangular, 2-2.5 inches long, and 2.5-3 inches wide. In growing season, the leaves are shiny green with a thin yellow midrib, erose margins, and a yellow, flattened stem. Leaves are bright yellow in the fall. The flowers are catkins 2-3.5 inches long and reddish. Groups of 0.5-inch ovate, seed-bearing fruit capsules cluster, splitting into three or four parts. The Rio Grande Cottonwood blooms from March through July, depending on the location. There is a high level of cross-reactivity among the species in the genus, Populus. This genus includes several species of cottonwood, poplar, and aspen. This group is closely related to willow species.