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Acacia heterophylla subsp. koaia

(Hillebr.) Morden & Faccenda (2025)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Eudicot-Rosids Order: Fabales Family: Fabaceae Genus: Acacia

dwarf koa, koa‘ohā [koaoha], koai‘a [koaia], koai‘e [koaie]

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Description

Key Characters:

Growth Form: Shrub to small tree up to 9 m tall.

Stems: Trunk gnarled and twisted, no spines.

Roots: Taprooted.

Leaves: Leaves compound (bipinnate) or modified into phyllodes of petiolar origin often with extrafloral glands on leaf rachises. Alternate. Phyllodes strongly falcate, 6–12 cm long, 0.8–1 cm wide, bipinnately compound leaves of various sizes present at apex of small phyllodes in sapling stages. Margins of phyllodes entire. Phyllodes with three prominent veins. Petiolate. Stipules absent.

Flowers: Flowers in heads, ca. 8 rnm in diameter (excl. stamens), these few together in axillary racemes or sometimes aggregated into terminal leafy panicles, peduncles ca. 1 cm long. Flowers mimosaceous, ca. 2 mm long. Calyx campanulate, truncate or obscurely 4–5-toothed. Petals cream color. Stamens numerous, curled, more than twice as long as corolla. Pollen born in tetrads. Ovary superior, pubescent.

Fruit: Pods flattened; curved and constricted between the seeds; 10–15 cm long; 0.8–1.0 cm wide; sutures straight or occasionally constricted between some of the seeds. Apex with a recurved mucro. Seeds oblong laterally flattened; transversely or longitudinally arranged.

Ploidy:

Habitat: Lowland and montane forests in both dry and wet forests.

Elevation Range: 300–1,800 m.

Historical Distribution

Images

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Uses and Culture

USES

  • To treat illnesses on the skin, koai‘a leaves and bark, ‘auko‘i (Senna occidentalis) and kikania stalks (Desmodium sandwicense) are ground together. Water is added and the mixture is heated; the patient takes a steam bath or puholoholo (Chun 1994:1156–157).

  • Wood, which is harder than the koa, was used for spears and decorative paddles; primary wood used for beaters (Hillebrande 1888:112; Krauss 1993:63). Wood also used for house timbers and carved fish hooks (Krauss 1993:43; Lamb 1981:47–48; Malo 1951:21), also in musical instrument (‘ukeke) (Krauss 1993:85).

  • Yellow dye from flowers

CULTURE

  • He Kaao no Palila Palila used a koai‘e wood pololu. (Fornander [v.5 part i] 1918:151).

PROPAGATION/CULTIVATION

  • Intermediate. Presoak seeds; when seedlings reach 10 cm begin to fertilize, plantout in full sun at height of 30-50 cm, lightly fertilize & water well; are highly drought resistant; monitor for insects (Bornhorst 1996:60–61; Bornhorst and Rauch 1994:15–16; Culliney and Koebele 1999:81–83).

Natural History

Statewide Status

Endemic

Island Status

Kaua'i Endemic
O'ahu Endemic
Molokai Endemic
Lana'i Endemic
Maui Endemic
Hawai'i Endemic

Dispersal Agents


Pollinators

Bibliography

Name Published In: Records of the Hawaii Biological Survey for 2025 p.110 (2025)

Other References

Wagner et al. 1990:641 (Mo, L, M, H [Syn. Acacia koaia = A. koa]); Wagner & Herbst 1999:1875 (RESURRECT, also K, perhaps O [as A. koaia]); Rico-Arce 2007:108 (DESCR [as A. koaia]); Morden & Faccenda 2025:110 (COMBNOV, STATNOV, Syn. A. koaia = A. heterophylla subsp. koaia); Thomas, Magnacca, et al. 2025:240 (O presence confirmed)

Occurrences

SNo. Scientific Name Scientific Name Authorship Locality Habitat Basis of Record Recorded By Record Number Island Source Date
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