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. Kanawao is a widespread species occurring in mesic and wet forests on all of the main Hawaiian Islands. It is a dioecious, evergreen plant that either grows as a 1.5–3-metre (4.9–9.8 ft) shrub or a 6-metre (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.