Black oak

Leaves

Form

• Base rounded
• 5–7 lobes
• Each lobe oblique or at a right angle to the midvein
• Sides of lobes parallel
• Separated by deep U-shaped notches
• Hairy early in the season
• Later a few stellate hairs remain on veins and in the vein axils of the lower surface 
• Lower surface rather rough

Length

• 10–20 cm
• Central lobe may be twice as long as leaf width between opposite notches

Colour

• Upper surface shiny dark green
• Lower surface yellowish-brown

Margin

• A few coarse bristle-tipped teeth

Petiole

• Stout
• 7–15 cm long

Buds

Form

• Terminal bud ovoid, sharp-pointed
• Distinctly angled
• Scale surfaces obscured by woolly hairs

Length

• 6–8 mm

Colour

• Woolly hairs greyish-white

Twigs

Form

• Moderately stout
• Hairless or slightly hairy

Colour

• Dark reddish-brown

Flowers

Form

• Pollen flowers small
• In many-flowered drooping catkins
• Seed flowers small
• Solitary or in few-flowered clusters (spikes)

Structure

• Monoecious

Floral timing

• With the leaves

Fruits

Form

• Acorns small
• Cup bowl-shaped enclosing about one-half of the nut
• Scales loose-fitting, thin, slightly hairy
• Sometimes forming a fringe to the cup

Length

• Acorns 12–20 mm

Width

• Almost as wide as long
• Cup 12–24 mm

Colour

• Cup dull brown

Structure

• 1-seeded nut

Bark

Form

• Smooth when young, becoming deeply furrowed with irregular, rounded ridges
• Ridges divided into squarish segments

Colour

• Dark grey when young, becoming almost black
• Inner bark yellowish

Wood

Colour

• Light brown

Size

Height

• To 20 m

Diameter

• To 90 cm

Maximum age

• 200 years

Tree form

Forest-grown

Trunk

• Distinct up to the crown

Crown

• Irregular, variable
• Principal branches horizontal in lower crown
• Principal branches ascending in upper crown

Root system

• Deep, wide-spreading, with a deep taproot

Habitat

Site

• Dry sandy soils
• Also on steep slopes with heavy soils

Light tolerance

• Intolerant of shade

Associated species

• Mixed with other broadleaf species

Range

Southern Ontario north of Lakes Erie and Ontario