August Tree of the Month: Eastern Cottonwood

Eastern Cottonwood (Populus deltoides)
by Martin (Mort) Schmidt for Simply Living

Cottonwood has alternate, simple leaves. In trees with alternate leaves (and branches), which describes most Ohio hardwoods, the leaves and branches are not attached directly across from each other, as shown in the image below. 

Simple leaves are distributed more or less randomly on a tree, and do not occur in regular groupings of 3, 5, 7, etc. Simple leaves are also attached to the tree with their own stem, instead of sharing a stem with two or more other leaflets. 

Cottonwood leaves have no lobes, but they have teeth and are triangular in shape; hence the species name deltoides. The leaf is somewhat shiny, which makes its shimmering in summer breezes all the more obvious. 

Eastern cottonwood and sycamore are the giants of creeks and floodplains. Cottonwood is easy to spot from a distance because of its large size and because its leaves quiver in the slightest wind, like it’s close relative quaking aspen (Populus tremuloides). Cottonwood has little commercial value today, but it played an important role in American history. 

Cottonwood grows rapidly and can reach a height of 60 ft in 15 years and a diameter of 6 ft in as little as 50 years, generally topping out at around 125 ft in height (Donald Culross Peattie – A Natural History of Trees of Eastern and Central North America). The bark is deeply furrowed and light gray colored, which together with its often large size, make it easy to distinguish in winter. Of course the common name, cottonwood, comes from the cotton-like substance that keeps the tiny seeds aloft and distributes them widely in the summer. 

Cottonwood lumber has little commercial value. We often use the words “hardwood”, “deciduous”, and “broadleaf” interchangeably to describe non-conifers, and “softwood”, “evergreen”, and “conifer” to describe coniferous trees. But these terms are generalizations. Not all hardwoods have hard wood, and cottonwood lumber is softer than some so-called softwoods. 

Wood hardness is complicated to measure, but because of their close correlation, lumber hardness is often expressed in terms of its density. According to Wood-database.com, Eastern cottonwood has a density of 0.45 g/cc, meaning that it’s 45% as dense as water. For comparison, white oak has a density of 0.75 g/cc. 

Cottonwood is too soft for quality furniture, and far too soft for flooring or other high-wear applications. Cottonwood tends to warp as it dries, it doesn’t hold nails well, and it becomes fuzzy when not worked with sharp tools. Like most light colored woods, cottonwood has poor rot resistance, and like other lightweight woods, it has little fuel value. And because cottonwood resists splitting, it couldn’t be split into firewood anyway. Furthermore, because cottonwood often occurs near streams, it’s generally difficult to access for harvesting. 

Cottonwood was once widely used to make boxes and crates. Its softness and light color make it useful for paper pulp. And like countless other woods of low commercial value, cottonwood is often made into shipping pallets. 

Cottonwood played an interesting role in American history. When members of the Lewis and Clark Expedition were traveling upstream toward the Rocky Mountains, they abandoned their larger boat and made dugout canoes to navigate the smaller streams. Those dugouts were made of cottonwood. Cottonwood’s softness made it workable with hand tools, and its split resistance kept the boats from cracking and leaking. And when it became necessary to portage the canoes, they rolled them on wheels sliced from cottonwood logs. Wheels of most other woods would have split. 

Ironically, while cottonwood is a water-loving tree, it’s often the most prominent tree in desert areas. As the pioneers migrated across the Western U.S., they sought out cottonwoods as sources of shade and indicators of nearby water. Long before the arrival of Europeans, the Hopi people discovered that cottonwood was ideal for making kachina dolls. Its softness makes it easy to work, and it’s split resistance enables artists to add facial features, limbs, and other details that aren’t apt to break off. Despite cottonwood’s low rot resistance, its relative abundance and large size in the arid West led to its wide use in the construction of buildings. Rot resistance was not the chief concern in a region with little rain. 

The cottonwood tree does not provide food for humans, but like other poplars and the closely-related willows (genus Salix), cottonwood is a source of salicylic acid, the active ingredient of aspirin. Consequently, the native Americans extracted substances from cottonwood leaves to reduce pain and swelling, and as a treatment for a snakebite (Fred Hageneder – The Meaning of Trees). 

A cottonwood tree was also used in the sacred Sun Dance ceremony of the Sioux Indians. A tree was selected a year before the ritual, and shortly before the ritual, cut down and placed into a hole at the ceremony grounds. Celebrants danced around the tree for 4 days and nights, and some chose to have their chest pierced with an eagle claw and attached to the Tree of Life with rope. The Sioux also saw the rustling of cottonwood leaves as a sort of prayer (Hageneder). 

Likewise, let us speak well of cottonwoods. Despite their limited commercial value, cottonwood trees are things of beauty and they’ve served us well through history.