Koai'a
Acacia koaia

Family: Fabaceae

What it is like

Closely related to koa (A. koa), and is sometimes considered to be the same species. Acacia koaia is usually distinguished by growing as a short (rarely more than 5 m or 16 ft), broad, gnarled tree; having the seeds longitudinally arranged in the pod; shorter, straighter phyllodes; and much denser wood. It has been devastated by cattle and other ungulates and is now rare.

Acacia koaia is an evergreen Tree growing to 5 m (16ft) by 5 m (16ft) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 10. It can fix Nitrogen. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.

Height (m): 5

Where it is found

Highly adapted to dry habitats, and is capable of forming dense forests in areas with very little rainfall. It was formerly found widely in dry forests on all of the main islands. Associated plants include uluhe (Dicranopteris linearis), hala (Pandanus tectorius), ko?oko?olau (Bidens spp.), koki?o (Hibiscus kokio), nehe (Lipochaeta spp.), hala pepe (Pleomele spp.), and ?ohi?a lehua (Metrosideros polymorpha).

Hawaiian Islands.

Conservation Status: Status: Vulnerable B1ab(i,ii,iii).

Countries/locations it is found in

Hawaii, United States.

How it is used

Food

Rating: 0

Medicine

Rating: 1

Native Hawaiians used ground leaves and bark with 'au'auko'i (Senna occidentalis) and kikania pipili (Desmodium sandwicense) stalks to treat diseased skin. The mixture was then hydrated and used in a steam bath.

Other

Rating: 4

Carbon Farming Solutions - Agroforestry Services: nitrogen, crop shade (Agroforestry is a land-use management system in which trees or shrubs are grown around or among crops or pastureland). The wood of koai'a is harder and denser than that of koa. It was used to make la'au melomelo (fishing lures), hoe (paddles), ihe (short spears), pololu (long spears), 'o'o (digging sticks), 'i'e kuku (square kapa beaters), and papa olona (Touchardia latifolia scrapers). Koai'a leaves were used to cover hale lau koai'e (shelters and permanent sheds).

Agroforestry Services: Crop shade: Plants providing crop shade especially trees.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Agroforestry Services: Crop shade: Plants providing crop shade especially trees.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.

How it is grown

Climate: tropical, tropical highlands. Humidity: semi-arid to humid. Highly adapted to dry habitats, and is capable of forming dense forests in areas with very little rainfall. A. koaia has been severely impacted by ranching, agriculture and fires started by humans. Other threats to the species are feral goats and pigs, deer, and invasive alien plants. Carbon Farming Solutions - Cultivation: regional crop. Management: standard (Describes the non-destructive management systems that are used in cultivation).

Propagating it: The seed of most, if not all, members of this genus has a hard seedcoat and may benefit from scarification before sowing to speed up germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing. Once treated, seeds are sown in nursery beds. 1 week after germination, seedlings are transplanted into nursery tubes or bags. Seedlings are ready for transplanting into the field when they are approximately 20cm tall, (after 3-4 months in the nursery). Establishment by direct seeding or encouragement of natural regeneration is recommended as heart rot occurs during transplanting. One study recommends air-layering as the best vegetative propagation technique. The seeds are durable and easy to store. They germinate after many years of storage if kept in a cool, dry place. The most effective method for improving seed germination is mechanical scarification. However, hot water soaking works well and is a more practical method, seed should be soaked in boiled water for 24 hours. Seeds are seldom dispersed far from the tree and remain viable in the soil for up to 25 years.

Best place to grow:

Habit: Tree

Hardiness: 10-12

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: No shade

Moisture: Dry, moist

Things to keep in mind

Its other names

Local names

Acacia koaia, known as koai?a or koai?e in Hawaiian.

Synonyms

No synonyms are recorded for this name.