Broussaisia
Broussaisia arguta, the kanawao, is a species of perennial flowering plant in the Hydrangea family, Hydrangeaceae, that is endemic to Hawaii. It is the only species in the monotypic genus Broussaisia.
Etymology, Taxonomy and Classification
Brussaisia 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: Pu’aha’nui, Akiahala, Kupuwao, and Pi’ohi’a.
Morphology
It is a dioecious, evergreen plant that either grows as a 1.5–3 meter shrub or a 6 meter tree. The obovate leaves are 10–25 centimeters long and 4–9 centimeters 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 10mm in diameter.
Ecology and Range
Kanawao is a widespread species occurring in mesic forests|mesic] and wet forests on all of the main Hawaiian Islands, typically between 305–1829 meters elevation.The Orthotylus broussaisia from Kaua'i feeds on Broussaisia arguta. Although there has been extensive research on Broussaisia arguta, only the Orthotylus broussaisiae species has been found feeding on it.
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 Po’ouli, declared extinct in 2019 and whose diet consisted of primarily insects and land snails, could be found foraging on B. arguta.