Bidens micrantha

Bidens micrantha is a species of flowering plant in the aster family known by the common name grassland beggarticks. It is endemic to the Hawaiian Islands, where it and other Bidens species are known as kōokoolau. It occurs in many types of habitat on Lānai, Maui, and Hawaii, including rocky cliffs, Hawaiian [tropical dry forests|dry forests], Hawaiian [tropical rainforests#Mixed mesic forests|mesic forests], wet forests, and high shrublands.
;Subspecies

While B. m. ssp. micrantha is considered secure, B. m. ssp. ctenophylla is uncommon and vulnerable and
B. m. ssp. kalealaha is rare and Endangered [Species Act|federally listed] as an endangered species.
This is a shrub forming clumps of herbage up to several feet tall. It bears plentiful flower heads with yellow ray florets. It is grown as an ornamental plant and groundcover in Hawaii.
This species was used to make leis and was brewed into tea.