Scientific Name
Populus sargentii
The plains cottonwood is one of the few natives in the Denver area, though it would’ve been far more likely to be found along one of the few local watercourses — such as down the hill at Clear Creek — rather than on the ridge where Regis is situated. Plains cottonwood, the state tree of Wyoming, grows in the wet places of dry regions, notably along the river corridors that cross the Great Plains and as such was a near constant shade-providing companion to the early pioneers moving westward. This tree is a close relative of the eastern cottonwood and is often considered a subspecies. Like its other relatives the aspen and the willow, its leaves have flattened stems that flutter in the slightest breeze, and it thrives in wet floodplain habitats.
Many of the most massive trees in the Denver region are plains cottonwoods; they’ve been planted here since early European settlement because they were obviously adapted to the environment. Though the younger stems may have smooth bark, the older trunks develop impressively thick ridges and furrows. The shapes of the mature trees tend to be off-center, partly because their weak wood lends itself to unpredictable limb breakage. The waxy-finished leaves are some of the broadest in the cottonwood/poplar/aspen group (all of the same genus), and the fat olive-yellow buds on thick winter twigs show the tree’s impatience for spring to arrive. In the fall, the leaves typically turn a bright golden yellow. These trees are either male or female, producing flowers on hanging catkins in early spring. By early summer the female flowers develop into hordes of tiny seeds attached to downy puffs that fly off and seem to float annoyingly everywhere. Like many trees in its family, this one can root freely from broken off twigs and in nature it often spreads this way with twigs floating away on floodwater, later becoming lodged in mud. In Denver, the typical plains cottonwood quickly grows to a height of around 75 feet; this is one of the fastest-growing tree species. In fact, its capacity for fast growth often leads to its age being estimated as greater than it is in reality.
Unfortunately, these trees are not noted for their longevity, with 75 to 90 years being a reasonable lifespan for them in urban conditions. For all their shortcomings, their iconic image as massive historic sentinels of the Great Plains means that they will likely always be present in Front Range cities as long as space allows.