Populus angustifolia James
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Family: Salicaceae
Genus: Populus
Species Synonyms: Populus balsamifera var. angustifolia (James) S. Wats.
Populus canadensis var. angustifolia (James) Wesmael
Populus fortissima A. Nels. & J.F. Macbr.
Populus salicifolia Raf.
Populus X sennii Boivin
Populus tweedyi Britt.
Common Names: narrowleaf cottonwood
Canada: southwestern Alberta – southwestern Saskatchewan
Saskatchewan: southwestern Saskatchewan; Cypress Hills
Ecoregion: Cypress Hills
Saskatchewan: small creek valleys
Canada: streambanks, plains, and foothills
Provincial Status According
to Harms (2003):
Nature Conservancy Status:
G5 S1
Saskatchewan Species at
Risk Status:
Narrowleaf cottonwood is endangered because it is extremely rare and regionally restricted in Saskatchewan. This species is almost always locally sparse. Immediate or probable threats have been identified.
Height: to 15 m
Stems: diameter at breast height (dbh) 20 – 50 cm; bark greenish to light brown, shallowly roughened on lower portion of truck, smooth above; branches ascending, orangey to greenish-brown; branchlets hairless; winter buds reddish, sticky, hairless
Leaves: alternate, simple, leaf stalk short and round, blade 5 – 12 cm long, lance-shaped to oval, base wedge-shaped to shallowly heart-shaped, tip acute to long-tapered, dark green above, pale green below, margins finely round-toothed
Inflorescence: catkins appearing with the leaves, drooping, 3 – 8 cm long, rachis slightly hairy or hairless; flower stalks to 1.5 mm long
Flowers: regular; bracts membranous, torn or lobed, early deciduous; nectar-disc cup-shaped, 1 – 2 mm wide; in male flowers stamens 10 – 20, filaments free; in female flowers ovary conic or ovoid, stigmas 2 – 4
Fruits: capsule nearly stalkless, 3 – 7 mm long, narrowly oval, wrinkled; seeds bearing tufts of long, white, silky hairs
1 Blades lance-shaped to narrowly oval, at least 1.5 times as long as wide
1 Blades oval to triangular, less than twice as long as wide
2 Leaf blades saw-toothed in the middle of the leaf; stamens 25 – 40; blades green on both sides
P. x acuminata
2 Leaf blades saw-toothed along the whole margin; stamens 10 – 25; blades lighter on the underside
3 Leaf stalks less than 1 cm long, less than one-third the length of the blade
P. angustifolia
3 Leaf stalks greater than 1 cm long, more than one-third the length of the blade
4 Leaves pale green to white, but not strongly bluish-waxy beneath; base wedge-shaped; first-year twigs orangey
P. x brayshawii
4 Leaves white and strongly bluish-waxy beneath; base rounded; first-year twigs reddish
P. balsamifera ssp. balsamifera
5 Leaf stalks strongly flattened; stamens 6 – 12; bark on trunk mostly smooth, usually white
P. tremuloides
5 Leaf stalks round or nearly so for most of their length or flattened; stamens 15 – 80; bark on trunk roughened, usually grey
6 Blades of early leaves oval, tip short-tapered; winter buds very sticky and fragrant
P. balsamifera ssp. balsamifera
6 Blades of early leaves triangular; tip long-tapered; winter buds very or slightly sticky, not fragrant
7 Blades of early leaves dark green above, light green below; margin coarsely saw-toothed or round-toothed, largest teeth 1 – 2 mm; leaf stalks nearly round
P. x jackii
7 Blades of early leaves light green above and below; margin coarsely round-toothed or saw-toothed or square-toothed, largest teeth 2 – 6 mm; leaf stalks flattened at the junction with the blade
8 Flower stalks 1 – 6 mm long; leaf base with 2 prominent glands
P. deltoides ssp. monolifera
8 Flower stalks longer than 6 mm; leaf base with 3 – 5 prominent glands
P. deltoides ssp. deltoides