The plains cottonwood is the state tree of Wyoming. There was some confusion about its scientific name — many people referred to it as Populus sargentii, while some scientists believed it was simply a subspecies of the eastern cottonwood, or Populus deltoides. It was first selected by Wyoming's legislature to be the state tree in February 1947. Then in 1961, the legislation amended the statute to clarify the tree's scientific name as Populus deltoides.
The plains cottonwood was chosen to be the state tree of Wyoming for two reasons. First, the changing weather in Wyoming agreed with the cottonwood, allowing the trees to grow well. As a result, the early pioneers in Wyoming began to plant the trees to create shade, causing them to increase in number across the area. Second, there was a large plains cottonwood in Thermopolis, Wyoming, that people believe represented the ideal tree. Consequently, the tree was chosen to be the state tree.
Although most plains cottonwoods only grow to 40 or 50 feet (about 12.2 or 15.2 m) in height, there are some claims that the trees are capable of reaching heights of nearly 100 feet (about 30.48 m). There were reports that the largest plains cottonwood was found in Albany County, Wyoming. As of 1990, the tree was only 64 feet (about 19.51 m) in height, causing many arborists to question the true height limits of the tree.
The leaves of the plains cottonwood are triangle-shaped. Many people believe they are similar in shape to an aspen leaf. The bark is gray in color, and the tree typically has yellow hanging flowers. The state tree of Wyoming also produces an abundance of cotton-like fruit. People often notice the fruit drifting through the air.
The plains cottonwood grows easily and quickly. Generally, the tree will live for an average of 70 years, but there are some reports of trees living for nearly a century. Although the tree prefers to live near water, especially near creeks, ponds, and lakes, it can survive in drier soils. If planted near a home, some care should be provided for the tree. For example, it should be watered and given seasonal fertilizer, pesticides, and insecticides. In addition, dying or damaged tree limbs should be removed to prevent disease from taking hold of it.
The biggest complaint regarding the state tree of Wyoming is its capacity for growing large roots. Specifically, if grown close to sidewalks, streets, or other man-made devices, the roots can lift the cement, wooden boards, asphalt, or concrete. If the damage producing roots are cut, it could kill the tree or cause it to be weaker over time.