Black walnut

Leaves

Form

• 14–22 short-stalked leaflets
• Central stalk moderately stout
• Terminal leaflet missing, or much smaller than largest lateral leaflets
• Middle leaflets larger than those at either end of leaf
• Upper surface smooth
• Lower surface faintly hairy

Length

• Leaf and central stalk 20–60 cm

Colour

• Upper surface yellowish-green

Buds

Form

• Terminal bud present, ovoid
• Slightly flattened, blunt, slightly hairy
• Leaf scars hairless

Length

• 8–10 mm

Colour

• Pale grey

Margin

• Leaf scars deeply notched on upper margin

Twigs

Form

• Stout, faintly hairy

Colour

• Orange-brown
• Pith orange-yellow

Flowers

Form

• Pollen flowers in catkins
• 20–30 stamens
• Seed flowers (spikes) in erect clusters of 1–4

Length

• Catkins 5–10 cm
• Seed flowers minute

Structure

• Monoecious

Floral timing

• Late May

Fruits

Form

• Globular
• In drooping clusters of 1–3
• Husk slightly hairy
• Nut surface with deep grooves and smooth-topped ridges
• Kernel strongly flavoured, oily

Width

• 4–6 cm 

Structure

• Nut

Bark

Form

• Scaly when young, developing rounded intersecting ridges with age

Colour

• Light brown when young, becoming darker, almost black

Wood

Texture

• Heavy, hard, strong
• Decay-resistant

Colour

• Dark brown to black
• Sapwood nearly white

Morphology

• Semiring-porous, straight-grained
• Easily worked and finished
• Not likely to shrink or warp

Figure

• Grain attractive

Uses

• Wood highly valued for furniture, panelling

Size

Height

• Up to 30 m

Diameter

• Up to 120 cm

Maximum age

• 150 years

Tree form

Forest-grown

Trunk

• Straight 

Crown

• Open, rounded
• A few large ascending branches

Root system

• Deep, wide-spreading
• Usually with a taproot

Habitat

Site

• Well-drained, fertile lowlands

Light tolerance

• Intolerant of shade

Associated species

• Found singly or mixed with other broadleaf trees

Range

Uncommon in Canada; occurring naturally in southern Ontario