Broussaisia

Kanawao
Vulnerable
Vulnerable (NatureServe)
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Cornales
Family: Hydrangeaceae
Subfamily: Hydrangeoideae
Tribe: Hydrangeeae
Genus: Broussaisia
Gaud.
Species:
B. arguta
Binomial name
Broussaisia arguta
Staminate (male) flowers

Broussaisia arguta, the kanawao, is a species of perennial flowering plant in the Hydrangea family, Hydrangeaceae, that is endemic to Hawaiʻi. It is the only species in the monotypic genus Broussaisia.

Etymology, Taxonomy and Classification

Broussaisia derives its name from Francois Joseph Victor Broussais, a physiologist from France. Arguta is a latin epitaph, which in biology, means “sharply toothed”, referring to the serrated margins of the leaf. Another commonly used scientific name is Hydrangea arguta.

The common Hawaiian name is Kanawao, but it is also referred to as: Puʻahaʻnui, Akiahala, Kupuwao, and Piʻohiʻa.

Morphology

It is a dioecious, evergreen plant that either grows as a 1.5–3 metres (4.9–9.8 ft) shrub or a 6 metres (20 ft) tree. The obovate leaves are 10–25 centimetres (3.9–9.8 in) long and 4–9 centimetres (1.6–3.5 in) wide with finely serrated margins

The flowers are arranged in a corymb, with male flowers being slightly longer than female flowers. Fertilized female flowers develop reddish blue berries about 10 mm (0.39 in) in diameter.

Ecology and Range

Kanawao is a widespread species occurring in mesic and wet forests on all of the main Hawaiian Islands, typically between 305–1,829 m (1,000–6,000 ft) elevation.

Orthotylus broussaisia (O. broussaisiae) from Kauaʻi feeds on Broussaisia arguta. Although there has been extensive research on Broussaisia arguta, only the Orthotylus broussaisiae species has been found feeding on it.[failed verification]

The leaves of B. arguta provides an advantageous habitat for the Hawaiian Happyface Spider as well as several species of native Hawaiian leafhoppers and several threatened species of endemic land snails. The Poʻouli, declared extinct in 2019 and whose diet consisted of primarily insects and land snails, could be found foraging on B. arguta.

Traditional Uses

The flowers and fruit can be eaten. Medicinally, the fruit was traditionally used to aid in conception and in the treatment of thrush and latent childhood disease. Certain varieties could only be consumed by men, while others could only be consumed by women and children.

References

  1. ↑ Walsh, S. (2025). "Hydrangea arguta". IUCN Red List of Threatened Species. 2025 e.T240434385A240434391. doi:10.2305/IUCN.UK.2025-2.RLTS.T240434385A240434391.en. Retrieved 31 August 2026.
  2. ↑ NatureServe. "Broussaisia arguta". NatureServe Explorer. Arlington, Virginia. Retrieved 23 October 2025.
  3. ↑ "Broussaisia arguta". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. 2008-07-01. Retrieved 2009-03-02.
  4. 1 2 3 4 5 Little Jr., Elbert L.; Roger G. Skolmen (1989). "Kanawao" (PDF). Common Forest Trees of Hawaii (Native and Introduced. United States Forest Service.
  5. 1 2 3 "Native Plants Hawaii - Viewing Plant : Broussaisia arguta". nativeplants.hawaii.edu. Retrieved 2025-11-15.
  6. 1 2 "Hydrangea arguta". Plants of Hawai'i. Bishop Museum. Retrieved 2025-11-15.
  7. ↑ Fosberg, F.R. (1939). "Taxonomy of the Hawaiian Genus Broussaisia (Saxifragaceae)" (PDF). Occasional Papers of Bishop Museum. XV (4).
  8. ↑ Gillespie, Rosemary G. (1990). "Costs and Benefits of Brood Care in the Hawaiian Happy Face Spider Theridion grallator (Araneae, Theridiidae)". The American Midland Naturalist. 123 (2): 236–243. doi:10.2307/2426552. ISSN 0003-0031. JSTOR 2426552.
  9. ↑ Bennett, Gordon M.; O’grady, Patrick M. (2011-03-30). "Review of the native Hawaiian leafhopper genus Nesophrosyne (Hemiptera: Cicadellidae: Deltocephalinae) with description of eight new species associated with Broussaisia arguta (Hydrangeaceae)". Zootaxa. 2805 (1): 1–25. doi:10.11646/zootaxa.2805.1.1. ISSN 1175-5334.
  10. ↑ Meyer III, Wallace M.; Evans, Lily M.; Kalahiki, Connor J. K.; Slapcinsky, John; Goulding, Tricia C.; Robinson, David G.; Kaniaupo-Crozier, D. Pomaikaʻi; Kim, Jaynee R.; Hayes, Kenneth A.; Yeung, Norine W. (January 2022). "Plants critical for Hawaiian land snail conservation: arboreal snail plant preferences in Puʻu Kukui Watershed, Maui". Oryx. 56 (1): 38–43. doi:10.1017/S0030605320000873. ISSN 0030-6053.
  11. ↑ Mountainspring, Stephen; Casey, Tonnie L. C.; Kepler, Cameron B.; Scott, J. Michael (1990). "Ecology, Behavior, and Conservation of the Poo-Uli (Melamprosops phaeosoma)". The Wilson Bulletin. 102 (1): 109–122. ISSN 0043-5643. JSTOR 4162828.