Black walnut

Silhouette - black walnut
  • Latin name: Juglans nigra L.
  • French name: Noyer noir
  • Synonym(s): American walnut
  • Taxonomic Serial Number: 19254
  • NA4 , C3
Description

Leaves

  • Leaf - black walnut
  • Leaflet with detail of finely toothed margin - black walnut

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

  • Lateral bud and leaf scar - black walnut

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

  • Winter twig - black walnut

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

  • Fruit with husk - black walnut

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

  • Silhouette - black walnut

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

Photos
  • Black walnut
  • Black walnut
  • Black walnut
  • Black walnut
  • Black walnut
  • Black walnut
  • Black walnut
  • Black walnut
  • Black walnut
  • Black walnut
Distribution map
Distribution map - black walnut
Date modified: