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Acacia heterophylla subsp. koa

(A.Gray) Morden & Faccenda (2025)

This name is accepted

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

koa

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Description

Key Characters:

Growth Form: Trees up to 35 m tall.

Stems:

Roots:

Leaves: Leaves compound (bipinnate) in the leaves of juvenile plants or modified into phyllodes of petiolar origin often with extrafloral glands on leaf rachises. Alternate. Leaves reduced to phyllodes, these narrowly elliptic and usually strongly falcate. 7.5–26 cm long, 0.5–2.5 cm wide. Margins of phyllodes entire. Petiolate. Stipules absent.

Flowers: Flowers bracteoles absent, flowers ca. 2 mm long, in heads ca. 8 mm in diameter (excl. stamens), these few together in axillary racemes or sometimes aggregated into terminal leafy panicles, peduncles ca. 1 cm long. Flowers mimosaceous. Calyx campanulate. Corolla cream–colored. Stamens numerous, curled, more than twice as long as corolla. Pollen born in tetrads. Ovary superior, pubescent.

Fruit: Pods flattened; oblong; 8–30 cm long; 0.8–2.5 cm wide; sutures straight or occasionally constricted between some of the seeds. Seeds ellipsoid; laterally flattened; either transversely or longitudinally arranged; 6–12 mm long; 4–7 mm wide.

Ploidy: 2n = 26*; 52*

Habitat: Often a dominant element of the vegetation in dry to wet forest.

Elevation Range: 60–2,060 m.

Historical Distribution

Images

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Uses and Culture

USES

  • Noted as "one of the most common trees on all islands...equally useful for fuel and construction"; trunks (in former times) used for great war canoes (Hillebrand 1888:113); bark for dye and tanning, all types of canoes, paddles (Degener 1930:177-8; Malo 1951:20); branches used in rituals (Malo 1951:174); bark for dye, wood for surfboards (Krauss 1993:65, 96); Abbott (1992:68) says no record of koa for traditional house building. Wood traditionally used as bearing sticks and kahili handles (Lamb 1981:47); now for furniture and bowls, but calabashes for food (‘umeke) were not traditionally made from koa as a bad taste was imparted. Wood also used in making weapons (Abbott 1992:110). Sometimes placed on hula altars (Pukui 1942). In the Ethnology Collection at Bishop Museum there is a contemporary example of koa used in part of a large pump drill.

  • Red dye from bark

  • The young leaves used to induce sleep for cramps or fevers; ashes of burnt leaves smeared on lesions for ‘ea (thrush) and pa‘ao‘ao in children (Chun 1994:156).

CULTURE

  • [I] E ola koa. Live like a koa tree. Live a long time, like a koa tree in the forest. [II] Ha‘alele i Puna na hoaloha e. Left in Puna are the friends. Said of one who has deserted his friends. Originally said of Hi‘iaka when she left Puna. [III] Ka ulu koa i kai o Oneawa. The koa grove down at Oneawa. From the legend of Hi‘iaka. Canoes are sometimes referred to as the koa grove at the sea, for canoes in ancient times were made of koa. [IV] Lihu‘e ho‘a wahie lala koa. Lihu‘e lights fires with koa branches. Lihu‘e, O‘ahu, once had a grove of koa trees whose brances were used for firewood.

PROPAGATION/CULTIVATION

  • Intermediate. Presoak seeds; roots emerge within a few days; higher elevations result in large, fine, straight trunks, fewer pests & disease; able to grow at sea level; monitor for insects (Bornhorst 1996:59–60; Culliney and Koebele 1999:77–81; Nagata 1992).

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

Notes

  • 300 m to about 1,800 m
  • Description digitized by Rafael Domingo
  • Description digitized from the Manual of the Flowering Plants of Hawaii
  • It is a canopy species like Ohia Lehua that dominate native forests. They can grow in dry or wet land
  • Not mention

Bibliography

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

Other References

Wagner et al. 1990:641 (K, O, Mo, L, M, H); Staples & Herbst 2005:301 (KEY), 302 (DESCR); Rico-Arce 2007:106 (DESCR), 108 (resurrect A. kauaiensis from synonymy of A. koa, not followed); Le Roux et al. 2014 (genetic evidence that A. koa is conspecific with A. heterophylla of Réunion Island); Morden & Faccenda 2025:110 (COMBNOV, STATNOV, Syn. A. koa = A. h. subsp. koa)

Occurrences

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