SCIENTIFIC NAME: Populus x acuminata
Growth habit The Lanceleaf cottonwood is found along streams in and near the foothills, and is characterized by its long leaf stalk and distinctive leaf shape, with maximum width at mid-length, not near the base of the leaf. It is found between 4500 to about 8500 feet in elevation, close to the same elevation range as the Narrowleaf cottonwood. It grows to 60 feet in height, with up to a 25-foot crown spread. Unlike other varieties, the Lanceleaf tends to produce a single stem, with an upright elliptical shape. Its limbs tend to be more slender and upright than on Plains cottonwood, but similar those of the Narrowleaf. The scientific name, acuminata, means “tapering to a point,” referring to the leaf shape.
Lanceleaf cottonwood reproduces from root suckers, and by layering (rooting) of branches buried in wet soil; following a flood, for example. Whether it can reproduce by seed is as yet unknown. There is a common belief that this tree is a hybrid of the Narrowleaf cottonwood and any of the varieties of Populus deltoides, such as the Plains or Rio Grande cottonwoods. All three of these cottonwoods – Plains, Narrowleaf, and Lanceleaf – are found together near the eastern foothills around 5500 feet, such as in the Garden of the Gods near Colorado Springs. However, Lanceleaf is found at higher elevations in the mountains than the Plains variety, and one specimen is found in Fort Bayard in southern New Mexico, hundreds of miles from the nearest Plains cottonwood. Therefore, Lanceleaf cottonwood may be a self-fertile variety, in which case it could grow from its own seed.
Foliage The leaf blade is 2-3.5 inches long, with a width of more than half the length. Leaf stalks are long, at least ½ to ¾ the length of the blade. Note that both the Narrowleaf cottonwood and Balsam poplar have short leaf stalks. Lanceleaf stalks are round and not flattened, with thick, glossy, leathery blades that are common to all cottonwoods. The leaf shape is intermediate between the Narrowleaf and Plains cottonwood leaf shape, and the leaf stalk is perhaps the most distinctive characteristic of this tree.
Landscape value The Lanceleaf cottonwood requires high soil moisture, as do other cottonwoods. It is a good tree to use in riparian areas, along waterways, or in low places where water consistently collects. The Lanceleaf variety has been used in several riparian restoration projects, including the Dry Creek restoration project in the St. Vrain Valley. It establishes best in hardiness zones 3-8. Due to its growth habit, it can be a structurally sound, unique and shapely selection for more moist planting sites.
Notes of interest In November of 2005, a Lanceleaf cottonwood in Timnath, CO, was nominated to receive State Champion Tree status. It ended up officially tying a tree in Fort Collins, CO, for this honor. The numbers for the tree in Timnath are 255 inches in circumference (81 inches in diameter at breast height), 95 feet tall and 75 feet in average crown spread. It is located on the banks of the Poudre River at the Poudre River Ranch, south of town. The tree was nominated by Denver resident Don Davis, who lived in Timnath while attending college in the 1950s.
Wendy McCartney, Colorado State Forest Service
Fossil Creek Current, November 2005
JoAn Bjarko, Timnath cottonwood ties for state champ honors
Stuart Wier, The Native Trees of the Southern Rocky Mountains: From Yellowstone to Santa Fe, 1998, 1999, 2002