Bidens amplectens possesses some of the largest flowers among the 22 endemic Hawaiian koʻokoʻlau. As with most Bidens spp., the leaves can be used to brew hot teas and tonics, and the flowers can be added to salads. Hawaiian Bidens spp. have barbless seeds, unlike the introduced Bidens species.

Growth Requirements

General

    Ko‘oko‘olau grow quickly in cultivation. It thrives in urban landscapes, large pots or containers, or vegetable gardens. While it is naturally drought-tolerant, it may require more water when cultivated, especially in pots. If grown in containers, consider repotting into larger containers as the size of the flowers and leaves may decrease after a year or two. Koʻokoʻlau can be grown as annuals or perennials, producing an abundance of seeds that easily regenerate within the pot or growing area.

    To ensure optimal growth, provide full sun, well-drained soil, and frequent watering during hotter months. For potted or container plants, use organic or natural fertilizers at a low dose, around one-fourth of the recommended strength, applied once or twice a month. Avoid over-fertilizing, particularly with nitrogen, as this can lead to large, floppy leaves and fewer flowers. Once planted in the ground in a permanent location, koʻokoʻlau generally does not require additional fertilizers.

    For consumption, adjust the nitrogen levels slightly to increase leaf yield or increase phosphorus for enhanced flower production. Organic fertilizers are preferred as they are less likely to burn foliage compared to synthetic options when used with native Hawaiian plants.

    Keep in mind, too, if you're growing more than one species and you want to maintain the purity of the species, that they easily cross, and you can end up with viable seeds that are a hybrid of the two or more other species if they are all flowering at the same time. If you have no concerns about this but plan on sharing seeds, it would be a kindness to let the person know that it may be a hybrid.

Pests and Diseases

    Red spider mites may infect the leaves. Refer to the Pests & Diseases page for treatments. 

Special Features and Information

General

    Koʻokoʻolau (Bidens spp.) are members of the Sunflower family (Asteraceae). There are about 20 or so endemic species of Bidens in the Hawaiian Islands.

    Pure Bidens amplectens is restricted to the windward cliffs and crests in its range. However, it does hybridize and intergrade with B. torta from near Ka‘ena Point to at least the head of Mākua Valley on the summit ridges of the Wai‘anae Mountains [Wagner et al. 1990].

Hawaiian Name

    Koʻokoʻolau, Koʻolau, and Kōkoʻolau are accepted names for the Hawaiian Bidens spp. [Hawaiian Dictionaries].

Etymology

    The generic name Bidens is derived from the Latin bi, meaning "two," and dens, meaning "teeth," in reference to the pappus awns or collective bristles on the achenes (fruit/seeds). The Latin specific epithet amplectens means "stem-clasping (leaf base)" [Gledhill 2008].