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EUCALYPTUS microtheca

Image of Eucalyptus microtheca

Michael Charters, www.calflora.net

Family

Myrtaceae

Botanical Name

EUCALYPTUS microtheca

Plant Common Name

Coolibah Tree

General Description

This large, evergreen tree is native to Northern Australia. The wood is extremely hard and difficult to work with but is excellent for firewood and makes long-lasting fence posts. Its trunk may be single or multi-stemmed and is often crooked. Rough, gray, platy and furrowed bark lines the trunk and adds landscape interest. The gray-green to blue-green leaves are long, lance-shaped and highly aromatic. They are flattened, smooth and flutter in the breeze. The flower clusters are grouped in branched stems at the ends of the branches. Each bloom is small and bristly with many white filaments. The small fruit is a light green conical capsule that ages to tan and is filled with black seeds.

Coolibah trees have a dense, rounded shape and are wind resistant. They are one of the most commonly planted eucalyptus species in the southwestern United States because they are lovely and easy to grow. Plant them in full sun and perfectly drained soil with average to poor fertility. Coolibah is quite cold tolerant, and will withstand below freezing temperatures. It is medium to fast growing and reaches a substantial size, so plant it where there is plenty of space. Prune while young to develop the desired stem number and branch structure. Coolibah trees are useful as shade and specimen trees. They also help to control erosion, so they are often planted to conserve soil.

Characteristics

  • USDA Hardiness Zone

    10 - 11

  • Sunset Zone

    H1, H2, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

  • Plant Type

    Tree

  • Sun Exposure

    Full Sun

  • Height

    30'-60' / 9.1m - 18.3m

  • Width

    24'-54' / 7.3m - 16.5m

  • Bloom Time

    Fall, Late Fall, Early Winter, Winter, Late Winter

  • Native To

    Australia

Growing Conditions

  • Soil pH

    Neutral, Alkaline

  • Soil type

    Clay, Loam, Sand

  • Growth Rate

    Fast

  • Water Requirements

    Xeric/Desert, Drought Tolerant

  • Habit

    Oval/Rounded

  • Seasonal Interest

    Spring, Summer, Fall, Winter

Ornamental Features

  • Flower Interest

    Insignificant

  • Flower Color

    White

  • Fruit Color

    White, Green

  • Foliage Color (Spring)

    Blue Green

  • Foliage Color (Summer)

    Blue Green

  • Foliage Color (Fall)

    Blue Green

  • Foliage Color (Winter)

    Blue Green

  • Bark Color

    White, Gray

  • Fragrant Flowers

    No

  • Fragrant Fruit

    No

  • Fragrant Foliage

    Yes

  • Bark or Stem Fragrant

    No

  • Flower Petal Number

    Single

  • Repeat Bloomer

    No

  • Showy Fruit

    No

  • Edible Fruit

    No

  • Showy Foliage

    No

  • Foliage Texture

    Medium

  • Foliage Sheen

    Glossy

  • Evergreen

    Yes

  • Showy Bark

    No

Special Characteristics

  • Bark Texture

    Fissured

  • Usage

    Feature Plant, Shade Trees, Street Trees

  • Sharp or Has Thorns

    No

  • Invasive

    Sometimes

  • Self-Sowing

    Yes