Black cottonwood

Leaves

Form

• Broadly ovate, tip long drawn-out
• Base usually rounded, sometimes wedge-shaped or slightly heart-shaped
• No warty glands at the base
• Lower surface mostly hairless

Length

• 7–12 cm

Colour

• Upper surface dark green
• Lower surface silvery green, usually stained with brownish resin blotches

Margin

• Finely toothed with many short, rounded teeth that turn inward at their tips (sometimes partially smooth)

Petiole

• Hairy
• Round in cross-section
• 3–4 cm long
• Green

Buds

Form

• Terminal bud round or slightly angled
• Slender, long-pointed
• Very resinous, fragrant
• 6–7 scales, sometimes fringed with hairs
• Lateral leaf buds parallel to the twig
• Pollen flower buds stout with thickened scales
• Leaf scars small, triangular

Length

• 17–20 mm

Colour

• Orange-brown

Twigs

Form

• Moderately stout, hairy
• Round to slightly angular in cross-section
• Lenticels large, sparse

Colour

• Orange-brown

Flowers

Length

• Pollen catkins 4–5 cm
• Seed catkins 6–8 cm

Structure

• Dioecious

Fruits

Form

• Mature seed catkins hairy, bearing many closely spaced capsules
• Capsules nearly globular, tip short
• Covered with short hairs
• Splitting into 3 parts when mature

Length

• Mature seed catkins 12–15 cm
• Capsules 3–4 mm
• Seeds 2 mm

Bark

Form

• Smooth when young, with age separating into flat-topped ridges with irregular V-shaped furrows

Colour

• Greyish-green or yellowish-grey when young, becoming dark greyish-brown

Size

Height

• To 35 m
• The largest broadleaf tree native to British Columbia

Diameter

• To 120 cm

Maximum age

• 165 years

Tree form

Forest-grown

Trunk

• Long, straight

Crown

• Narrow, somewhat columnar
• Open, with a few stout ascending branches

Root system

• Wide-spreading, with a few large roots, penetrating obliquely to the water table or a layer of hardened soil

Habitat

Site

• At lower and middle elevations
• On bottomlands
• Loose, porous, sandy or gravelly soils