All the flowers here represent the genus Bidens which has 19 endemic species in the Hawaiian Islands. They have daisy-like yellow flowers and are members of the Composite family.

It is thought that all evolved from one ancestral immigrant species through a process of adaptive radiation. Bidens species elsewhere in the world produce fruit called Spanish dagger or beggar's tick because of their sharp pointed ends which stick into skin, hair or clothing. The Hawaiian species have lost this trait and most dispersibility.

Hawaiians called the plants kokolau or koko'olau and used them medicinally. The leaves of koko'olau are still used to make an herbal tea. The plant on the left was found on Mt. Ka'ala.

The plant on the right is identified asBidens amplectans. The photos above were taken by Priscilla Millen.

The photo below, of Bidens cosmoides, was taken by Charles Lamoureux. Bidens cosmoides is found only on Kaua'i and its Hawaiian name is po 'ola nui.


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