Woody > Populus > Populus heterophylla > Populus heterophylla
Populus heterophylla
Origin: Populus heterophylla is found on the continental United States, predominantly along the east coast. There is a single location in Canada, south of Sarnia, Ontario, where the species can be found.
Mike's
Opinion
"
Like the Eastern Cottonwood, the Swamp Cottonwood is sparsely populated throughout its range of habitation. The tree is seemingly rare and is not largely valued for commercial purposes due to its difficulty in propagation from cuttings, and its similarity to the more popular Eastern Cottonwood -- which outperforms it except in swampy or wet soils. I think the tree may have more potential use and value than we know; however, the Swamp Cottonwood is under-studied and overshadowed by the favour of the Eastern Cottonwood.
Michael Pascoe, NDP., ODH., CLT., MSc. (Plant Conservation)
"
| Family |
| Salicaceae |
| Genus |
| Populus |
| Species |
| heterophylla |
| Category |
| Woody |
| Type |
| Tree (evergreen) |
| USDA Hardiness Zone |
| 5a |
| Canadian Hardiness Zone |
| 5a - 5b |
| RHS Hardiness Zone |
| H7 |
| Temperature (°C) |
| -29 |
| Temperature (°F) |
| -20 |
| Height |
| 30 - 40 m |
| Spread |
| 0.9 - 1.9 m |
Photographs
Cultivars
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Description and Growing Information
Flowering Period
| General Description |
| A woody deciduous tree with brownish bark (potentially with a tinge of red), that developing fissures and furrows as the tree matures. Alternating leaves that are broadly ovate. The species is dioecious, meaning that there are separate male and female trees with male and female flowers respectively. The tree’s seeds are covered with cotton-like hairs along their catkins. |
| Landscape |
| The wood of Populus heterophylla is so similar to that of Populus deltoides that its lumber is often sold as the same wood. Pulp and paper, crates, and parts of furniture are among the few commercial uses, but there seems to be no market for specifically Populus heterophylla. The tree is useful for flood and erosion control in some small, local areas. Swamp Cottonwood is rarely cultivated for ornamental use in the landscape. Overall, the species is overshadowed by the Eastern Cottonwood. |
| Cultivation |
| Swamp Cottonwood prefers wet clay soils near swamps and low-lying areas near tide waters. The pH range of its root medium should be between 4.6 and 5.9. The species needs plenty of sun but with moist soil in order to thrive. It is intolerant to shade. Safe to say it would not like most urban environments. Growing this species could prove tricky given the chance that sunlight will dry out the root medium of the tree, but the tree requires a lot of sunlight. |
| Shape |
| The tree’s shape appears to be dependent on the individual specimen and its conditions. |
| Growth |
| Fast |
| ID Characteristic |
| Alternating leaves that are broadly ovate and cordate at their base. Cottenlike hairs on the tree’s seeds along its catkins. The leaf base sometimes overlaps the summit of the petiole. The female flowers have a long and slender style compared to other species of the same genus. Note that this species can easily be misidentified with other Cottonwoods. |
| Pests |
| There are no known diseases or insects that affect Populus heterophylla. However, it is considered likely that diseases and pests that affect Populus deltoides will affect Populus heterophylla. Common insects that plague Populus deltoides are: cottonwood leaf beetle, cottonwood twig borer, poplar borer, and cottonwood borer. Diseases that may also affect Populus heterophylla include: Septoria, Cytospora, Fusarium, and Melampsora leaf rust. Deer and beavers are also considered a potential threat to the species. |
| Habitat |
| Populus heterophylla is poorly understood in terms of its exact hydrological requirements. However, it seems to prefer particular areas of wet or swampy soils; particularly shorelines of lakes, swamps, wetlands, wet woods, lowlands, bottomlands, and floodplain forests. |
| Bark/Stem Description |
| The Swamp Cottonwood’s bark matures from green to dull brown, sometimes with a bit of red, with narrow plates. |
| Flower/Leaf Bud Description |
| The buds are overwintering, reddish brown in colour, somewhat pubescent, slightly resinous, 1.0 - 1.5 cm long, and canescent-tomentose towards their bases. |
| Leaf Description |
| Alternating leaves that are broadly ovate, cordate at their base, and measure 12-20 cm in length. The leaves appear after the flowers, emerging around mid-May with pinnate venation and densely white hair. They remain semi-hairy after reaching maturity. The petioles are noticeably terete or round. The adaxial is dark green, while the abaxial is pale green. The margins are unevenly crenate-serrate with sinuses 0.3 - 1 mm deep. |
| Flower Description |
| The flowers are wind-pollinated. The flowers appear from March to May. The flowers are catkin. The male catkin is an open and erect raceme 5 - 7 cm long, roughly 15 mm thick, and substantially enlarges as the flowers mature. The female catkins are also raceme and are 2 - 5 mm long until after fertilization, when the catkin expands to be a fruit. Male catkins are yellowish, and the female catkins are green. |
| Fruit Description |
| After fertilization, the female flower expands into the fruit that is about 7 - 12 mm in length, and is attached to a pedicel 10 - 15 mm long. The seeds are produced from April through July. The mature fruit has 2 - 3 valves. The fruits, like the catkins, are raceme in arrangement. The seeds are covered by fine white cotton-like hairs. |
| Colour Description |
| The bark of the tree is a dull brown, perhaps with some red. The branches are white while young and change as they mature to be more like the bark in colour. The leaves are green, and there seems to be no description of any autumn colours. The male catkins are yellowish, and the female catkins are green. The fruit appears white with its cotton-like hairs. |
| Texture Description |
| The bark is deeply fissured or furrowed, so one might consider it generally coarse in texture. Its branches start out tomentose, becoming glabrous as they mature. The texture seems to remain the same throughout the seasons. |
| Propagation |
| Female trees can reproduce after roughly ten years. The seeds are only viable for about 1 - 2 weeks. The seeds prefer shadeless, full-sun, bare, wet, clay, or loam soils. It is imperative to have full sun without the soil drying out. The use of cuttings may work; however, more studies must be done on Populus heterophylla to ensure optimal propagation methods. Cuttings seem to be a difficult method of choice for propagating Populus heterophylla. So, it is perhaps best to stick with seed-based propagation. More study is required for the species. If one were to attempt propagation, a good reference point might be the propagation protocol for Populus deltoides: Sow the seeds immediately after they ripen, as they have a small time frame of viability. Storing the seeds and maintaining their viability may be possible if the moisture content is reduced to 4 - 5 percent; the viability should be maintained for six months or more. Either sow the seeds directly onto the soil's surface or use a cold frame and seed trays. With the seed tray and cold frame method, start by sowing seed into seed trays. Then, remove the seedlings and plant them into individual pots when they are big enough to be moved, and place the pots into the cold frame. If developed enough, the specimens may be able to be planted in late summer; if not, plant them in late spring. For either method, the seedlings require constant moisture for several weeks to establish their slow-developing root systems. Seedlings will germinate, if viable, between 48 and 120 hours after sowing. The seedlings will be fragile for three weeks as they grow. Once planted and under the right conditions, the seedlings should grow for 3 - 5 months and then harden off once their growing season ends (if sufficient root establishment has occurred). |
| Ethnobotanical Uses (Disclaimer) |
| The plant is largely ignored and rarely used in ornamental or commercial applications. The plant is mostly if not almost completely relegated to wild populations that are quite sparse and small. The bark contains a glycoside called salicin, which breaks down into salicylic acid (aspirin) in the body. Thus, the bark is anti-inflammatory, febrifuge, and anodyne. The bark is prominently used for fevers, rheumatism, menstrual cramps, intestinal warms, colds, scurvy, whooping cough and tuberculosis. The leaves are used to make a poultice for treating sores, boils, and bruises. |
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