Cottonwood (the genus Populus) is composed of 35 species which contain the aspens and poplars. Species in this group are native to Eurasia/north Africa [25], Central America [2] and North America [8]. All species look alike microscopically. The word populus is the classical Latin name for the poplar tree.
Populus angustifolia balsam, bitter cottonwood, black cottonwood, lanceleaf cottonwood, mountain cottonwood, narrowleaf cottonwood, narrow leaved poplar, Rydberg cottonwood, smoothbark cottonwood, willow cottonwood, willowleaf cottonwood
Populus balsamifera balm, balm of Gilead, balm of Gilead poplar, balm cottonwood, balsam, balsam cottonwood, balsam poplar, bam, black balsam poplar, black cottonwood, black poplar, California poplar, Canadian balsam poplar, Canadian poplar, cottonwax, hackmatack, hairy balm of Gilead, heartleaf balsam poplar, northern black cottonwood, Ontario poplar, tacamahac, tacamahac poplar, toughbark poplar, western balsam poplar
Populus deltoides* aspen cottonwood, big cottonwood, Carolina poplar, cotton tree, eastern cottonwood, eastern poplar, fremont cottonwood, great plains cottonwood, Missourian poplar, necklace poplar, northern fremont cottonwood, palmer cottonwood, plains cottonwood, Rio Grande cottonwood, river cottonwood, river poplar, southern cottonwood, Tennessee poplar, Texas cottonwood, valley cottonwood, Vermont poplar, Virginia poplar, water poplar, western cottonwood, whitewood, wislizenus cottonwood, yellow cottonwood
Populus fremontii Arizona cottonwood, Fremont cottonwood, Fremont poplar, meseta cottonwood, valley cottonwood, wislizenus cottonwood
Populus heterophylla bigleaf cottonwood, black cottonwood, cotton gum, cotton tree, cottonwood, downy cottonwood, downy poplar, river cottonwood, swamp cottonwood, swamp poplar
Populus trichocarpa* balsam cottonwood, black cottonwood, California poplar, cottonwood, western balsam poplar
*commercial species
Distribution: Most of North America, with Populus deltoides in the eastern to midwest United States and Populus trichocarpa in the western United States.
The Tree: Cottonwood trees can reach heights of 190 ft (77 m), with a diameter of 6 ft (2.4 m).
General Wood Characteristics: The sapwood of cottonwood is white, while the heartwood is light brown to brown. The wood is weak in bending and compression, soft and low in shock resistance. It has a sour odor when wet, but no characteristic odor or taste when dry. Tension wood is frequently present, causing a fuzzy surface when cut.
Weight
Weightb
Species MC SGa lb/ft3 kg/m3
Populus Green 0.31 40 641
balsamifera
(balsam 12% 0.34 23 368
poplar)
Ovendry 0.35 NA NA
Populus Green 0.37 49 785
deltoides
(eastern 12% 0.40 28 449
cottonwood) Ovendry 0.43 NA NA
Populus Green 0.31 46 737
trichocarpa
(black 12% 0.35 24 384
cottonwood)
Ovendry 0.37 NA NA
aReferences: specific gravity, green and
12%, (98);
specific gravity, ovendry, (59).
bReference (59).
Mechanical properties
Property Green Dry
Populus balsamifera (balsam poplar)a
MOE 0.75 106 5.171 GPA 1.10 106 7.585 GPa
lbf/in2 lbf/in2
MOR 3.90 103 26.891 MPa 6.80 103 46.886 MPa
lbf/in2 lbf/in2
C| | 1.69 103 11.653 MPa 4.02 103 27.718 MPa
lbf/in2 lbf/in2
C 0.14 103 0.965 MPa 0.30 103 2.069 MPa
lbf/in2 lbf/in2
WML 4.2 28.959 5.0 in-lbf/in3 34.475
in-lbf/in3 kJ/m3 kJ/m3
230 lbf 1023.04 N 300 lbf 1334.40 N
Hardness
Shear| 0.50 103 3.447 MPa 0.79 103 5.447 MPa
| lbf/in2 lbf/in2
Populus deltoides (eastern cottonwood)b
MOE 1.01 106 6.964 GPa 1.37 106 9.446 GPa
lbf/in2 lbf/in2
MOR 5.30 103 36.544 MPa 8.50 103 58.608 MPa
lbf/in2 lbf/in2
C| | 2.28 103 15.721 MPa 4.91 103 33.854 MPa
lbf/in2 lbf/in2
C 0.20 103 1.379 MPa 0.38 103 2.620 MPa
lbf/in2 lbf/in2
WML 7.3 50.334 7.4 in-lbf/in3 51.023
in-lbf/in3 kJ/m3 kJ/m3
340 lbf 1512.32 N 430 lbf 1912.64 N
Hardness
Shear| 0.68 103 4.688 MPa 0.93 103 6.412 MPa
| lbf/in2 lbf/in2
Populus trichocarpa (black cottonwood)b
MOE 1.08 106 7.446 GPa 1.27 106 8.757 GPa
lbf/in2 lbf/in2
MOR 4.90 103 33.786 MPa 8.50 103 58.608 MPa
lbf/in2 lbf/in2
C| | 2.20 103 15.169 MPa 4.50 103 31.028 MPa
lbf/in2 lbf/in2
C 0.16 103 1.103 MPa 0.30 103 2.069 MPa
lbf/in2 lbf/in2
WML 5.0 34.475 6.7 in-lbf/in3 46.197
in-lbf/in3 kJ/m3 kJ/m3
250 lbf 1112.00 N 350 lbf 1556.80 N
Hardness
Shear| 0.61 103 4.206 MPa 1.04 103 7.171 MPa
| lbf/in2 lbf/in2
aReference (98) except for hardness (59).
bReference (98).
Drying and shrinkagea
Percentage of shrinkage
(green to final moisture
content)
Type of shrinkage 0% MC 6% MC 20% MC
Tangential
Populus balsamifera (balsam 7.1 NA NA
poplar)
Populus deltoides (eastern 9.2 7.4 3.1
cottonwood
Populus trichocarpa (black 8.6 6.9 2.9
cottonwood)
Radial
Populus balsamifera (balsam 3.0 2.9 1.2
poplar)
Populus deltoides (eastern 3.9 3.1 1.3
cottonwood
Populus trichocarpa (black 3.6 2.9 1.2
cottonwood)
Volumetric
Populus balsamifera (balsam 10.5 NA NA
poplar)
Populus deltoides (eastern 13.9 11.3 4.7
cottonwood
Populus trichocarpa (black 12.4 9.9 4.1
cottonwood)
aReferences: 0% MC, (98); 6% and 20% MC (90).
Kiln drying schedulea,b
4/4, 5/4, 8/4 10/4 12/4 16/4
Condition 6/4 stock stock stock stock stock
Normal T10-F5 T8-F4 T6-E3 T5-D2 NA
wood
Wet T8-D5 T6-C4 T4-D3 T3-D2 NA
streaks
aSchedule for Populus balsamifera (balsam poplar),
P. deltoides (eastern cottonwood), P. heterophylla
(swamp cottonwood), P. sargentii (plains
cottonwood) and P. trichocarpa (black cottonwood).
bReferences (6, 86).
Working Properties: Cottonwood glues well, has low nail-holding ability, does not split easily, and holds paint well.
Durability: Rated as slightly or nonresistant to heartwood decay.
Preservation: No information available at this time.
Uses: Lumber, veneer, plywood short bolts, pulpwood, boxes, crates, food containers, interior furniture parts, agricultural implements, wooden ware, cutting boards.
Toxicity: Sawdust may cause dermatitis (40, 64, 105).
Additional Reading: 29, 49, 55, 68, 74. 55, 66, 68, 74, 79. 28, 29, 42, 43, 44, 48, 50, 55, 56, 68, 72, 73, 74, 79, 92, 97, 102. 74, 75, 77, 99, 106. 101.