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ALNUS japonica

Image of Alnus japonica

Russell Stafford

Family

Betulaceae

Botanical Name

ALNUS japonica

Plant Common Name

Japanese Alder

Special Notice

This entry has yet to be reviewed and approved by L2G editors.

General Description

Glossy green leaves and the persistent brown seed fruits make Japanese alder a great shade tree with a broad adaptability to landscape soils and moisture. A pyrimad-shaped deciduous tree that does not get too wide, it hails from Japan, Korea and China's Manchuria. Its barks becomes light gray-sandy brown with shallow fissures.

In early spring this tree flowers. The male flowers are in drooping, finger-like clusters called catkins and are yellow-brown. The female flower are small and purplish and occur along the twigs on very short stems. After wind pollination, the green cylindrical fruits form and ripen to a sienna brown before shedding the winged seeds. The dried fruits persist on the branches into fall and winter. The leaves are glossy dark green, tapered ovals with minute irregular teeth. No notable fall leaf coloration occurs.

Grow Japanese alder in average garden soils that are moist to wet, or average well-draining. It is adaptable to acidic and alkaline soils regardless of fertility. It will tolerate drier conditions and occasional flooding! It is best in regions with cool summers, and in the warmest parts of USDA zone 7 and 8 it may only grow as if a large shrub. This species is fast growing and also works well as a windbreak in addition to being a specimen shade tree for park or avenue. Use it to vegetate the water's edge or in drier infertile soils where little else will cast shade.

Characteristics

  • AHS Heat Zone

    7 - 4

  • USDA Hardiness Zone

    5 - 8

  • Sunset Zone

    1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21

  • Plant Type

    Tree

  • Sun Exposure

    Full Sun, Partial Sun, Partial Shade

  • Height

    55'-70' / 16.8m - 21.3m

  • Width

    25'-30' / 7.6m - 9.1m

  • Bloom Time

    Early Spring

  • Native To

    China, Japan, Korea

Growing Conditions

  • Soil pH

    Acidic, Neutral, Alkaline

  • Soil Drainage

    Average

  • Soil type

    Clay, Loam, Sand

  • Tolerances

    Wet Site, Drought

  • Growth Rate

    Fast

  • Water Requirements

    Drought Tolerant, Average Water

  • Habit

    Pyramidal

  • Seasonal Interest

    Spring, Summer, Fall

Ornamental Features

  • Flower Interest

    Insignificant

  • Flower Color

    Purple, Light Yellow, Sandy Brown

  • Fruit Color

    Sienna, Chocolate

  • Foliage Color (Spring)

    Green

  • Foliage Color (Summer)

    Green, Dark Green

  • Foliage Color (Fall)

    Green, Dark Green

  • Bark Color

    Sandy Brown, Gray

  • Fragrant Flowers

    No

  • Fragrant Foliage

    No

  • Bark or Stem Fragrant

    No

  • Repeat Bloomer

    No

  • Showy Fruit

    Yes

  • Edible Fruit

    No

  • Showy Foliage

    Yes

  • Foliage Texture

    Medium

  • Foliage Sheen

    Glossy

  • Evergreen

    No

  • Showy Bark

    No

Special Characteristics

  • Bark Texture

    Fissured

  • Usage

    Feature Plant, Screening / Wind Break, Shade Trees, Street Trees

  • Sharp or Has Thorns

    No

  • Invasive

    No

  • Self-Sowing

    Yes