Home › Cupressaceae › Juniperus (junipers)

Native range: Northern hemisphere southward to tropical Africa

Western juniper (14149478156)

Leaves:

  • awl-shaped, whorled and spreading or scale-like
  • often both leaf types on same plant

Jun chin close

Cones:

  • dioceious
  • male cones:
    • small
    • catkin-like
    • wind pollinated
  • female cones:
    • 3-8 scales that fuse and become round and fleshy (berry-like) when ripe
    • covered with wax
    • purple/blue or black or occasionally red
    • usually <1/2” across
    • 1-3 seeds per scale
    • ripen and atten full size in the 1st autumn after pollination
    • berries mature by Nov. or Dec. of the 2nd year after pollination, then remain on the tree until March or April of the following spring

Western juniper berries

Other notes:

  • trees up to 90 ft. (usually smaller) or prostrate shrubs
  • evergreen
  • cones are used to flavor gin and smell like gin when crushed
  • wood of tree junipers used for drawers or to line closets (repel moths)
  • in PNW, native species include:
    • J. communis (common juniper)
    • J. occidentalis (western juniper)
    • J. scopulorum (Rocky Mountain juniper, seaside juniper), which lives 250-300+ years

Ecology & Adaptations:

  • J. communis:
    • found throughout much of Canada and the United States
    • dry, open lowland woods, gravelly ridges, outcrops, muskeg and open rocky slopes
    • from lowland bogs to mountain valleys to subalpine ridges and alpine tundra
  • J. scopulorum:
    • found in Puget Trough and SW British Columbia, south, east Cascades, to Oregon on coastal islands to inland valleys and lower mountains
  • J. occidentalis:
    • found east of the Cascades in desert foothills and lower mountains
  • adventitious root development can occur when branches come in contact with the ground or become buried (aid in water and nutrient intake)
  • pollination by wind
  • seed dispersal of common juniper - gravity, water, mammals, and especially birds (such as waxwings)
    • digestive (acidic) processes do not harm most juniper seeds and may enhance germination
  • herbivore/microbial defense – compounds such as terpenoids and volatile oils deter herbivory by mule deer and microbial infection, though leaves are susceptible to rust and several borers and beetles
  • wildlife – many bird species nest or roost in foliage
  • fire resistance:
    • resistant when mature, when they develop thicker bark and a more open crown, allowing them to survive surface fires if the low, spreading branches do not carry fire to the crown
    • volatile oils makes younger plants more flammable
    • post-fire re-establishment is by seed (no re-sprouting)