Kauai plant has big bright yellow flowers
Description: A crawling shrub up to 4 feet tall with dark green serrated leaves and bright yellow flowers that hang inverted to the stem. Compared with other native members of the same genus (Ko'oko'olau), this species has the largest flowers -- up to 3 inches in diameter, compared with those from other species that might be just one-half to 1 inch across. One type of ko'oko'olau from Oahu (Bidens amplectans) has the same diameter flower, if not even wider, but is less massive. It is believed that due to its large flower size, po'ola nui might be pollinated by native birds, whereas other species of Bidens with smaller flowers are pollinated by insects or the wind.
This plant is only found naturally in mesic forests of Kauai.
Landscape use and care: This plant does well in partial shade but will also do OK in full sun. Well-drained soil with organic amendment is also recommended. Daily watering is fine, but a good soaking every couple of days would be better. This plant is not easy to find, so if you come across one, plant it where you can show off its beautiful flowers.
Other uses: Like other species of Bidens (Ko'oko'olau), the leaves and flowers of Po'ola nui can be made into a tea. Hint: Pick fresh leaves and flowers, wash, then brew. Gather enough to cover the surface of the water in whatever pot you use, then steep until the brew reaches the desired darkness.
Also: Many of us are familiar with the weed called Spanish needle or beggar's tick (Bidens pilosa), which bears little dark brown seeds with two barbs at the end that get stuck in our shoes, socks, pants, everything. Those barbs act as its dispersal mechanism. They hook onto large grazing mammals, such as cows or deer, and the animals then carry the seeds to different places. In Hawaii such large grazing mammals are few, so the plants had to adapt. Rather than barbed, the Hawaiian Bidens' seeds became twisted, curved or were more flattened out, all of which are better adaptations for wind dispersal.
co-owns Hui Ku Maoli Ola, a native Hawaiian plant nursery, with Matt Schirman. Contact him at 259-6580 or e-mail email@example.com