Populus is the Latin name for poplars. Deltoides refers to the triangular-shaped
leaves. Occidentalis is Latin for "west."
|| Cottonwoods are members of Salicaceae, the willow
family, along with willow (Salix spp.) and quaking aspen (Populus
tremuloides ). The leaves are deciduous, alternate, simple, 3 to 6 inches (8 to 15 cm) long, triangular-shaped with serrate margins. Flowers occur in the spring before the leaves appear, they are dioecious and in hanging catkins . Fruits are 1/4 inch (.64 cm) long, 3 or 4 valved capsules. The twigs are yellowish brown and smooth. The terminal buds are long and resinous. The bark is ash-gray and divided in thick flattened ridges with deep furrows.
Eastern cottonwood is found throughout the central United States. It occurs from New York to Kansas (where it is the state tree), as far north as central Minnesota and south to the Gulf of Mexico. In South Dakota, eastern cottonwood is native to the eastern 1/4 of the state.
Eastern Cottonwood Native Distribution
Plains Cottonwood Native Distribution
| Plains cottonwood is native throughout the central
plains from Texas to Manitoba. It occurs in the western 3/4 of South
Dakota. Some botanists believe these trees are not two different varieties and group them together as eastern cottonwood. Other botanists have separated the two into two species with plains cottonwood given the Latin name Populus sargentii . Regardless of the taxonomic split, the use and ecology of the two trees are similar and they are grouped together in this fact sheet.
Cottonwood, as with willow, is a pioneer species. It is also very intolerant
of competition. Cottonwoods tend to seed into a
new flood plain and develop as pure, even-aged stands. As cottonwoods mature (about 50-70 years after the stand begins),
they are gradually replaced by the more tolerant ash and elm. In some areas of central South Dakota, cottonwood has an
understory of eastern red cedar (Juniperus virginiana ).
The two greatest threats to cottonwood are fire and drought. Cottonwoods
are very vulnerable to fire, light burns will kill
seedlings and saplings. Hotter fires can severely injure the bark on older trees, which opens the trees up to decay. While they
are moderately drought tolerant, a long-term dry spell will lead to death.
Life Span: Cottonwood is not a very long-lived tree. As with
their close relative, willow, cottonwoods usually live about
70 years. A 120 year old cottonwood is a very old tree.
Size: While cottonwoods may not live very long, they are very
fast growing so big trees are a common sight. The largest
cottonwood is in Grundy County, Illinois. It is 373 inches (947 cm) in circumference, 132 feet (40 m) tall with a branch
spread of 99 feet (30 m). The largest in South Dakota is a plains cottonwood near Richland in Union County. It is 344 inches
(873 cm) in circumference, 114 feet (35 m) tall with branch spread of 113 feet (34 m).
Wood of the cottonwood is light. It was important as a construction
material for the American Indians and European settlers.
Cottonwood, because of its abundance, was used to build barns and houses. Occasionally large cottonwoods, 4 to 6 feet (123
to 183 cm) in diameter, were cut down and burned out to form a crude canoe. Today cottonwood is used for pulp and
sometimes lightweight furniture. Cottonwood is also used as a windbreak species although it is not highly recommended due
to its short life expectancy. Two common windbreak cottonwoods used today are Siouxland (P. deltoides 'Siouxland') and
Northwest (x P. 'Northwest'). Siouxland is a cottonless male cultivar developed in South Dakota. It is losing popularity due
to susceptibility to several diseases. Northwest is a hybrid of P. deltoides and balsam poplar (P. balsamifera ). It is fast
growing and has a longer life span.
The Dakota ate the sweet inner bark of young sprouts of cottonwood trees
in the spring. They also fed young cottonwood
branches to their horses. A dye was made from the leaf buds. The Sacred Pole, used in ceremonies of the Omaha Indians, is
made of cottonwood.
Publication of the Eastern and Plains Cottonwood fact sheet was
funded by the S.D. Department of Agriculture, Division of
Forestry, Pierre, SD.