Jack pine
Description
Leaves
Form
- Needles evergreen
- In bundles of 2
- Straight or slightly twisted, stiff
- Sharp-pointed, spread apart
- Edges toothed
- Bundle-sheath persistent
Length
- 2–4 cm
Colour
- Light yellowish-green
Buds
Form
- Blunt-pointed, resinous
Length
- To 15 mm
Colour
- Pale reddish-brown
Twigs
Form
- Slender, ridged and grooved
- Vigorous shoots on young trees usually with 1 or more intermediate nodes bearing loose whorls of side branches
Colour
- Yellowish-green becoming dark greyish-brown in second season
Seed cones (mature)
Form
- Variable in shape
- Oblong to conical, asymmetrical
- Straight or curved inward
- Stalkless, usually pointing forward
- Often in clusters of 2 or 3 at nodes
- Usually remaining closed and persistent on the tree for 10–20 years
Length
- 3–7 cm
Colour
- Yellowish-brown when mature
Structure
- 80 scales, thickened at the tips
- Smooth (sometimes with a minute prickle)
- Held closed by a resin bond
Timing
- Open when exposed to heat from a wildfire or sometimes from direct sunlight on warm days
Seeds
Form
- Often ridged
Length
- Seed 3 mm
- Seed wing about 10 mm
Colour
- Dark brown or black
Seedlings
Form
- 3–6 cotyledons, toothless
Lenght
- 12–24 mm
Bark
Form
- Thin when young, becoming flaky
- With age furrowed into irregular thick plates
Colour
- Reddish-brown to grey when young, becoming dark brown
Wood
Texture
- Moderately hard and heavy, weak
Colour
- Light brown
Uses
- General construction, wood pulp, railway ties, poles, pilings, and mine timbers
Size
Height
- To 20 m, occasionally larger
Diameter
- To 30 cm
Maximum age
- 150 years
Tree form
Open-grown
Trunk
- Tapered
Crown
- Conical, open
- Branches ascending, arching
Forest-grown
Trunk
- Slender, straight, with little taper
Crown
- Short
Root system
- Wide-spreading, moderately deep
- Often with a taproot
Habitat
Site
- Coarse sands, shallow soils, and rock out-crops, permafrost
- On poor soils and rocky sites, tree short, often twisted, with long stout branches, some dead or dying, giving the crown an unkempt appearance
- After extensive fires, jack pine may occupy all sites from ridge tops to muskegs
Light tolerance
- Intolerant of shade
Associated species
- Grows in pure stands or mixed with other shade-intolerant species such as white birch, trembling aspen, balsam poplar, red pine, and tamarack
- Shade-tolerant species such as black spruce, white spruce, and balsam fir often form the understory
Range
Most widely distributed pine in Canada
Insects and diseases
Insects
- Eastern pine shoot borer
- Gray spruce looper
- Jack pine resin midge
- Metallic pitch blister moth
- Northern pine weevil
- Northern pitch twig moth
- Pine measuringworm moth
- Pine needle sheathminer
- Pine zale
- Redheaded pine sawfly
- Red pine cone beetle
- Red pine sawfly
- Small pine looper
- Striped ambrosia beetle
- Swaine jack pine sawfly
- Western pine elfin
- Jack pine budworm
- Mountain pine beetle
- Pine false webworm
- Spruce budworm
- Warren root collar weevil
- White pine weevil
- Feralia comstocki Grote
- Fir coneworm
- Pales weevil
- Pine needle scale
- Pine shoot beetle
- Pine spittlebug
- Pine tortoise scale
- Spruce spider mite
- Whitespotted sawyer
Diseases
- Brown rot
- Comandra blister rust
- Needle cast (Lophodermium pinastri )
- Needle rust of pine
- Pinicola brown crumbly rot
- Red ring rot
- Scleroderris canker, European strain
- Sericeomollis brown cubical butt
- Stalactiform blister rust
- Tar spot needle cast
- Western gall rust
- Annosus root and butt rot (Heterobasidion irregulare)
- Armillaria ostoyae root disease
- Armillaria root rot
- Brown cubical sap rot
- Diplodia tip blight (Sphaeropsis sapinea)
- Lodgepole pine dwarf mistletoe
- Pine needle cast
- Red heart rot
- Scleroderris canker North American strain
- Sirococcus Shoot Blight
- Sweetfern blister rust
Insects and diseases that are found most frequently and/or that cause the most damage in our Canadian forests.
Distribution map

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