Acacia koa

Source: Wikipedia, the free encyclopedia.
"Koa" redirects here. For other uses, see Koa (disambiguation).

Acacia koa
A young koa tree showing compound leaves and phyllodes

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fabales
Family: Fabaceae
Subfamily: Caesalpinioideae
Clade: Mimosoid clade
Genus: Acacia
Species:
A. koa
Binomial name
Acacia koa
Synonyms[2]

Acacia heterophylla var. latifolia Benth.
Acacia kauaiensis Hillebr.

Racosperma koa (A.Gray) Pedley

Acacia koa, commonly known as koa,[3] is a species of flowering tree in the family Fabaceae. It is endemic to the Hawaiian Islands,[2] where it is the second most common tree.[4] The highest populations are on Hawaiʻi, Maui and Oʻahu.

Name

The name koa in the

Eusideroxylon zwageri (togas in Tombonuwo), and Intsia bijuga (dort in Palauan) descend from this root.[5]

Koa also means brave, bold, fearless, or warrior.[3]

Description

Upper branches of a koa tree, showing the bark, sickle-shaped phyllodes, greenish rounded flower heads, and seedpods

Koa is a large tree, typically attaining a height of 15–25 m (49–82 ft) and a spread of 6–12 m (20–39 ft).[6] In deep volcanic ash, a koa tree can reach a height of 30 m (98 ft), a circumference of 6 m (20 ft), and a spread of 38 m (125 ft).[7] It is one of the fastest-growing Hawaiian trees, capable of reaching 6–9 m (20–30 ft) in five years on a good site.[8]

Leaves

Initially, bipinnately compound leaves with 12–24 pairs of leaflets grow on the koa plant, much like other members of the pea family. At about 6–9 months of age, however, thick sickle-shaped "leaves" that are not compound begin to grow. These are phyllodes, blades that develop as an expansion of the leaf petiole. The vertically flattened orientation of the phyllodes allows sunlight to pass to lower levels of the tree. True leaves are entirely replaced by 7–25 cm (2.8–9.8 in) long, 0.5–2.5 cm (0.20–0.98 in) wide phyllodes on an adult tree.[6]

Flowers

Flowers of the koa tree are pale-yellow spherical racemes with a diameter of 8–10 mm (0.31–0.39 in).[9] Flowering may be seasonal or year round depending on the location.[6]

Fruit

Fruit production start occurring when a koa tree is between 5 and 30 years old. The fruit are legumes, also called pods, with a length of 7.5–15 cm (3.0–5.9 in) and a width of 1.5–2.5 cm (0.59–0.98 in). Each pod contains an average of 12 seeds. The 6–12 mm (0.24–0.47 in) long, 4–7 mm (0.16–0.28 in) wide seeds are flattened ellipsoids and range from dark brown to black in color. The pods are mature and ready for propagation after turning from green to brown or black. Seeds are covered with a hard seed coat, and this allows them to remain dormant for up to 25 years. Scarification is needed before A. koa seeds will germinate.[9]

Habitat

Koa is

canopy of Hawaiian mixed mesic forests.[11] It is also common in wet forests.[12]

Uses

The American Pop singer Taylor Swift with a Taylor acoustic guitar made of Acacia koa wood

The koa's trunk was used by

outrigger canoes)[13] and papa heʻe nalu (surfboards). Only paipo (bodyboards), kikoʻo, and alaia surfboards were made from koa, however; olo, the longest surfboards, were made from the lighter and more buoyant wiliwili (Erythrina sandwicensis).[14] The reddish wood is very similar in strength and weight to that of Black Walnut (Juglans nigra), with a specific gravity of 0.55,[9] and is now sought for use in wood carving and furniture.[6] Koa is also a tonewood,[15] often used in the construction of ukuleles,[16] acoustic guitars,[17] and Weissenborn-style Hawaiian steel guitars.[18]

Stratocaster in 2006. Trey Anastasio, guitarist for the band Phish, primarily uses a koa hollowbody Languedoc guitar. Commercial silviculture of koa takes 20 to 25 years before a tree is of useful size.[21]

A thinly sliced section of wide Hawaiian Koa lumber

Taylor, Collings and Martin are few among the many other brands that use that tonewood for manufacturing acoustic guitars. [22]

Relation to other species

sister species, Acacia melanoxylon. Dispersals most likely occurred via seed-carrying by birds such as petrels.[25] Both species have very similar ecological niches, which differ from that of A. melanoxylon.[25]

A closely related species, koaiʻa or koaiʻe (A. koaia), is found in dry areas. It is most easily distinguished by having smaller seeds that are arranged end-to-end in the pod, rather than side by side. The phyllodes are also usually straighter, though this character is variable in both species. The wood is denser, harder, and more finely grained than koa wood.[6] Koaiʻa has been much more heavily impacted by cattle and is now rare, but can be seen on ranch land in North Kohala.[citation needed]

Conservation

The koa population has suffered from grazing and

outrigger canoes, there are few koa remaining which are both large and straight enough to do so today.[6] In areas where cattle are present, koa regeneration is almost completely suppressed. However, if the cattle are removed, koa are among the few native Hawaiian plants able to germinate in grassland, and can be instrumental in restoring native forest. It is often possible to begin reforestation in a pasture by disk harrowing the soil, as this scarifies seeds in the soil and encourages large numbers of koa to germinate.[10] Experiments at the Hakalau Forest National Wildlife Refuge have shown that ʻōhiʻa lehua (Metrosideros polymorpha) survives best in pasture when planted under koa. This is because koa trees reduce radiative cooling, preventing frost damage to ʻōhiʻa lehua seedlings.[26]

Ecology

Koa is the preferred

sap is eaten by the adult Kamehameha butterfly (Vanessa tameamea).[28] The koa bug (Coleotichus blackburniae) uses its rostrum to suck the contents out of koa seeds.[29] Koa is vulnerable to infection by koa wilt
.

Gallery

References

  1. ^ Contu, S. 2012. Acacia koa. The IUCN Red List of Threatened Species 2012: e.T19891713A19999145. https://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T19891713A19999145.en. Downloaded 8 May 2017.
  2. ^ a b "Acacia koa". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 2010-05-03.
  3. ^
    ISBN 978-0-8248-1994-1
    .
  4. ^
    University of Hawaiʻi at Mānoa
    . Retrieved 2009-01-31.
  5. ^ Blust, Robert; Trussel, Stephen (2010). "*teRas: heartwood of a tree, hard, durable core of wood; ironwood tree". Austronesian Comparative Dictionary. Max Planck Institute for Evolutionary Anthropology. Retrieved 27 December 2022.
  6. ^ a b c d e f g Elevitch, Craig R.; Kim M. Wilkinson; J. B. Friday; C. Baron Porter (April 2006). "Acacia koa (koa) and Acacia koaia (koaiʻa)" (PDF). The Traditional Tree Initiative. {{cite journal}}: Cite journal requires |journal= (help)
  7. ISBN 978-0-8225-4685-6
    .
  8. ISBN 978-0-9702544-2-9
    .
  9. ^ a b c Allen, James A. (2003-01-01). "Acacia koa A. Gray" (PDF). Tropical Tree Seed Manual. Reforestation, Nurseries & Genetics Resources. Retrieved 2009-02-23.
  10. ^ a b Whitesell, Craig D (1990). "Acacia koa". In Burns, Russell M.; Honkala, Barbara H. (eds.). Hardwoods. Silvics of North America. Vol. 2. Washington, D.C.: United States Forest Service (USFS), United States Department of Agriculture (USDA). Archived from the original on 20 January 2009. Retrieved 2009-02-17 – via Southern Research Station.
  11. ISBN 978-0-8248-2190-6
    .
  12. ISBN 978-0-8248-1096-2
    .
  13. ISBN 978-1-4446-7820-8
    .
  14. ISBN 978-0-7603-2753-1
    .
  15. ^ Beberman, Norman L. "Koa: Beautiful Looking, Beautiful Sounding Tonewood". GuitarNation.com. Archived from the original on 7 February 2009. Retrieved 2009-02-23.
  16. ISBN 978-3-8024-0446-7
    .
  17. ISBN 978-1-890490-21-8
    .
  18. ISBN 978-0-8264-6322-7
    .
  19. ISBN 978-0-933224-18-6
    .
  20. ^ Kirkland, Eric (December 2006). "Rich and Famous". Guitar World: 154.
  21. ^ "Silviculture: Diversification of Rural Economy". Leeward Haleakalā Watershed Restoration Partnership. Retrieved 2009-02-01.
  22. ^ "Is Koa Wood The Ultimate Choice For Guitar Enthusiasts?". Best Guitars Now. Retrieved 2023-11-24.
  23. United States Forestry Service. {{cite journal}}: Cite journal requires |journal= (help
    )
  24. PMID 24943937
    .
  25. ^
    PMID 24942529
    .
  26. ^ Friday, J. B.; Darrell A. Herbert (April 2006). "Metrosideros polymorpha ('ōhi'a lehua)" (PDF). The Traditional Tree Initiative: 21. {{cite journal}}: Cite journal requires |journal= (help)
  27. ISBN 978-0-8047-2013-7
    .
  28. ISBN 978-0-935848-93-9
    .
  29. ^ "Koa Bug Investigation" (PDF). Uhh.hawaii.edu. Retrieved 15 March 2022.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Acacia_koa&oldid=1186688347"