Acacia koa

Koa, with its frequently curly grain and attractive coloration, is considered the most valuable of the common native timber species in Hawaii.
Photo Credit: © Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.
Acacia koa
Common Name: koa
Plant Functional Group: Evergreen broadleaf
Class > Order > Family: Magnoliopsida > Fabales > Fabaceae
What does the species look like?

Koa is an evergreen tree, growing 50 to 140 foot tall. It has two types of leaves, changing from true leaves to sickle-shaped phyllodes (modified leaf stems) as conditions allow. Its tiny, pale yellow flowers have both male and female parts, are clustered into small globes, and are insect-pollinated.

Koa is found in Hawaii's cool, dry to mesic, montane rain forests, growing best in the high rainfall areas. It is found on volcanic soils of all geologic ages and degrees of development, requiring well-drained soils. It is a nitrogen-fixing species, and is intolerant of frost and shade.
Where is the species found?
States & Provinces
HI
Which phenophases should I observe?
Do you see...?
Leaves Young leaves
One or more young, unfolded leaves are visible on the plant. A leaf is considered "young" and "unfolded" once its entire length has emerged from a breaking bud, stem node or growing stem tip, so that the leaf base is visible at its point of attachment to the leaf stalk (petiole) or stem, but before the leaf has reached full size or turned the darker green color or tougher texture of mature leaves on the plant. Do not include fully dried or dead leaves. For Acacia koa, on mature trees only include the newly formed phyllodes that are soft to the touch and have bluish-green coloration, sometimes with a silvery sheen.

How many young leaves are present?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
Flowers Flowers or flower buds
One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds or inflorescences that are swelling or expanding, but do not include those that are tightly closed and not actively growing (dormant). Also do not include wilted or dried flowers.
More...

How many flowers and flower buds are present? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), simply estimate the number of flower heads, spikes or catkins and not the number of individual flowers.

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
Open flowers
One or more open, fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between or within unfolded or open flower parts (petals, floral tubes or sepals). Do not include wilted or dried flowers.
More...

What percentage of all fresh flowers (buds plus unopened plus open) on the plant are open? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), estimate the percentage of all individual flowers that are open.

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Fruits Fruits
One or more fruits are visible on the plant. For Acacia koa, the fruit is a pod that changes from green to brown and splits open to expose the seeds. Do not include empty pods that have already dropped all of their seeds.
More...

How many fruits are present?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
Ripe fruits
One or more ripe fruits are visible on the plant. For Acacia koa, a fruit is considered ripe when it has turned brown and has split open to expose the seeds. Do not include empty pods that have already dropped all of their seeds.
More...

What percentage of all fruits (unripe plus ripe) on the plant are ripe?

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Recent fruit or seed drop
One or more mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind, or empty fruits that had long ago dropped all of their seeds but remained on the plant.
More...

How many mature fruits have dropped seeds or have completely dropped or been removed from the plant since your last visit?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
What do these phenophases look like?

There is currently no photoguide available for this species. If you'd like help us create one, use the guidance document and species template provided here. Then send it via email to education@usanpn.org when it is complete.

ITIS information for koa (ITIS TSN: 182079 )
USDA PLANTS profile for koa (USDA Symbol: ACKO )