Cottonwood
Encyclopedia
Populus section Aigeiros is a section of three species in the genus Populus, the poplars. Commonly known as cottonwoods, the species are native to North America
, Aigeiros
and western Asia
. In the past, as many as six species were recognized, but recent trends have been to accept just three species, treating the others as subspecies of P. deltoides.
They are large, deciduous tree
s 20–45 m tall, distinguished by thick, deeply fissured bark
and triangular-based to diamond-shaped leaves
that are green on both sides (without the whitish wax on the undersides of balsam poplar leaves) and without any obvious balsam scent in spring. An important feature of the leaves is the petiole, which is flattened sideways so that the leaves have a particular type of movement in the wind.
Male and female flower
s are in separate catkin
s, appearing before the leaves in spring. The seeds are borne on cotton
y structures that allow them to be blown long distances in the air before settling to ground.
The cottonwoods are exceptionally tolerant of flooding, erosion
and flood deposits filling around the trunk.
Although each of the three cottonwood species has a different leaf pattern, they all have the same general diamond leaf shape.
Populus deltoides (eastern cottonwood) is one of the largest North American hardwood
trees, although the wood is rather soft. It is a riparian zone
tree. It occurs throughout the eastern
United States
and in extreme southern Canada
. The leaves
are alternate and simple, with coarsely-toothed (crenate/serrate) edges, and subcordate at the base. The leaf shape is roughly triangular, hence the species name, deltoides.
In the typical subspecies deltoides (Vermont
south to northern Florida
and west to about Michigan
), the leaves are broad and triangular, 7–15 cm across at the base. Further west (Minnesota
south to eastern Texas
), the subspecies monilifera (plains cottonwood; syn. P. sargentii) has somewhat narrower leaves, 5–10 cm wide at the base. This is also the state tree of Nebraska
, Wyoming
, and Kansas
. In West Texas, New Mexico
, and Colorado
, the subspecies wislizeni (Rio Grande cottonwood; syn. P. wislizeni) occurs.
Populus fremontii
(Fremont cottonwood) occurs in California
east to Utah
and Arizona
and south into northwest Mexico
; it is similar to the eastern cottonwood, differing mainly in the leaves having fewer, larger serrations on the edge, and small differences in the flower and seed pod structure. Some consider fremontii to be a subspecies of Populus deltoides.
Populus nigra (black poplar), native to Europe and western Asia, is distinct in its much smaller leaves, 5–11 cm across, with a more rhombic (diamond) shape.
production along wet river banks, where their exceptional growth rate provides a large crop of wood within just 10–30 years. The wood is coarse and of fairly low value, used for pallet boxes, shipping crates and similar purposes where a cheap but strong enough wood is suitable. They are also widely grown as screens and shelterbelts. Many of the cottonwoods grown commercially are the hybrid of eastern cottonwood and black poplar, Populus × canadensis (hybrid black poplar or Carolina poplar).
Cottonwood bark is often a favorite medium for artisans. The bark, which is usually harvested in the fall after a tree's death, is generally very soft and easy to carve.
Cottonwood is one of the poorest wood fuels; it does not dry well, and rots quickly. It splits poorly, because it is very fibrous. It produces a low level of BTUs
per cord
of wood.
Cottonwoods serve as food for the caterpillar
s of several Lepidoptera
(list of Lepidoptera that feed on poplars).
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, Aigeiros
Aigeiros
Aigeiros is a village and a former municipality in the Rhodope peripheral unit, East Macedonia and Thrace, Greece. Since the 2011 local government reform it is part of the municipality Komotini, of which it is a municipal unit. Population 4,418 ....
and western Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. In the past, as many as six species were recognized, but recent trends have been to accept just three species, treating the others as subspecies of P. deltoides.
They are large, deciduous tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s 20–45 m tall, distinguished by thick, deeply fissured bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
and triangular-based to diamond-shaped leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
that are green on both sides (without the whitish wax on the undersides of balsam poplar leaves) and without any obvious balsam scent in spring. An important feature of the leaves is the petiole, which is flattened sideways so that the leaves have a particular type of movement in the wind.
Male and female flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s are in separate catkin
Catkin
A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect pollinated . They contain many, usually unisexual flowers, arranged closely along a central stem which is often drooping...
s, appearing before the leaves in spring. The seeds are borne on cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
y structures that allow them to be blown long distances in the air before settling to ground.
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
and flood deposits filling around the trunk.
Although each of the three cottonwood species has a different leaf pattern, they all have the same general diamond leaf shape.
Populus deltoides (eastern cottonwood) is one of the largest North American hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
trees, although the wood is rather soft. It is a riparian zone
Riparian zone
A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by...
tree. It occurs throughout the eastern
Eastern United States
The Eastern United States, the American East, or simply the East is traditionally defined as the states east of the Mississippi River. The first two tiers of states west of the Mississippi have traditionally been considered part of the West, but can be included in the East today; usually in...
United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and in extreme southern Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are alternate and simple, with coarsely-toothed (crenate/serrate) edges, and subcordate at the base. The leaf shape is roughly triangular, hence the species name, deltoides.
In the typical subspecies deltoides (Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
south to northern Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
and west to about Michigan
Michigan
Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....
), the leaves are broad and triangular, 7–15 cm across at the base. Further west (Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
south to eastern Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
), the subspecies monilifera (plains cottonwood; syn. P. sargentii) has somewhat narrower leaves, 5–10 cm wide at the base. This is also the state tree of Nebraska
Nebraska
Nebraska is a state on the Great Plains of the Midwestern United States. The state's capital is Lincoln and its largest city is Omaha, on the Missouri River....
, Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, and Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
. In West Texas, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, and Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, the subspecies wislizeni (Rio Grande cottonwood; syn. P. wislizeni) occurs.
Populus fremontii
Populus fremontii
Populus fremontii, the Fremont cottonwood or Alamo cottonwood, is a cottonwood poplar native to western North America, in California and east to Nevada, Utah, Arizona, and New Mexico, and south into Sonora in northwestern Mexico...
(Fremont cottonwood) occurs in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
east to Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
and Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
and south into northwest Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
; it is similar to the eastern cottonwood, differing mainly in the leaves having fewer, larger serrations on the edge, and small differences in the flower and seed pod structure. Some consider fremontii to be a subspecies of Populus deltoides.
Populus nigra (black poplar), native to Europe and western Asia, is distinct in its much smaller leaves, 5–11 cm across, with a more rhombic (diamond) shape.
Cultivation and uses
Cottonwoods are widely grown for timberTimber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
production along wet river banks, where their exceptional growth rate provides a large crop of wood within just 10–30 years. The wood is coarse and of fairly low value, used for pallet boxes, shipping crates and similar purposes where a cheap but strong enough wood is suitable. They are also widely grown as screens and shelterbelts. Many of the cottonwoods grown commercially are the hybrid of eastern cottonwood and black poplar, Populus × canadensis (hybrid black poplar or Carolina poplar).
Cottonwood bark is often a favorite medium for artisans. The bark, which is usually harvested in the fall after a tree's death, is generally very soft and easy to carve.
Cottonwood is one of the poorest wood fuels; it does not dry well, and rots quickly. It splits poorly, because it is very fibrous. It produces a low level of BTUs
British thermal unit
The British thermal unit is a traditional unit of energy equal to about 1055 joules. It is approximately the amount of energy needed to heat of water, which is exactly one tenth of a UK gallon or about 0.1198 US gallons, from 39°F to 40°F...
per cord
Cord (unit of volume)
The cord is a unit of measure of dry volume used in Canada and the United States to measure firewood and pulpwood. A cord is the amount of wood that, when "ranked and well stowed" , occupies a volume of...
of wood.
Cottonwoods serve as food for the caterpillar
Caterpillar
Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...
s of several Lepidoptera
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
(list of Lepidoptera that feed on poplars).
External links
- Swamp Cottonwood, Populus heterophylla—Large-format diagnostic photographs, species information. Morton ArboretumMorton ArboretumThe Morton Arboretum, in Lisle, Illinois, covers 1,700 acres and is made up of gardens of various plant types and collections of trees from specific taxonomical and geographical areas. It includes native woodlands and a restored Illinois prairie. The Arboretum has over 4,100 different species of...
acc. 144-91-6 - Minnesota DNR big tree list. The largest tree by circumference in MinnesotaMinnesotaMinnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
is a Populus deltoides at 394 inches (1,001 centimeters) measured at the trunk 4 and 1/2 feet (137 cm) above the ground. This tree is 106 feet (32.31 meters) tall. - Monster Ohio Cottowood - 528 points in 2005—YouTubeYouTubeYouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....