Ko`oko`olau

Erect perennial herb in the Asteraceae (sunflower) family, woody at the base, 0.7 to 4 m (2.3 to 13 ft) tall, with sprawling horizontal lateral branches. Leaves are pinnately compound and bi- or tri-pinnatifid, or bipinnately compound, 7 to 29 cm (2.8 to 11 in) long. Flower heads are 5 to 20 in diffuse panicles or compound cymes terminating lateral branches only. Yellow ray and disk florets are often divergent so that flower heads have a loose, globose appearance. Achenes are brownish black, straight to curved, irregularly twisted or coiled, wingless or with narrow undulate wings. The subspecies pentamera with leaflets 5 to 9, shallow, and with ascending rounded toothed lobes.

The species historical range included Hawaii. See below for information about where the species is known or believed to occur.

Habitat Requirements

Historic and current collections of this subspecies suggest a more restricted distribution, but also of one that varies between west Maui and east Maui. On west Maui, Bidens campylotheca subsp. pentamera is found primarily in mid-elevation mesic areas from 940 m to 1,400 m (3,000 ft to 4,500 ft). These areas have average temperatures between 14° C (57° F) and 16° C (61° F), and annual precipitation ranging from 2,920 to 6,350 mm (115 inches (in) to 250 in). However, one population is in a much warmer and drier location with average temperatures up to 19° C (66° F) and annual precipitation only around 1,270 mm (50 in). On east Maui, B. campylotheca subsp. pentamera occurs in upper elevation mesic and wet forests and cliffs, with all records from above 1,250 m (4,000 ft). Temperatures for these populations are between 12° C (53° F) and 16° C (61° F) with annual rainfall ranging from 2,160 mm to 9,150 mm (85 in to 360 in). It is notable that this species has not been collected from the higher, wetter elevations of west Maui, with climatic variables within the range of the individuals on east Maui. On far eastern Maui in Kipahulu and Waihoi Valleys, subspecies pentamera occurs at higher and slighter drier sites than the narrow endemic subspecies waihoiensis, which occurs from 940 to 1,310 m (3,000 to 4,200 ft ) in elevation in very wet forest.

Food Habits

Movement / Home Range

Bidens campylotheca subsp. pentamera has occurred in high elevation wet and mesic forests on east Maui and mid-elevation dry to mesic forests of west Maui. Currently, this subspecies is found on east Maui in the montane mesic, montane wet, and wet cliff ecosystems of Waikamoi PR and Kipahulu Valley. On west Maui, B. campylotheca subsp. pentamera found on and near cliff walls in the lowland dry and mesic ecosystems.

Reproductive Strategy

All populations are mixed mating, which means they don’t exclusively outcross or self. This means that cross-pollination is important for the maintenance of population structure. Dispersal for Bidens species is usually by mechanical means via attachment to animals, such as birds. However, most Bidens species in Hawaii (including this subspecies) have lost or greatly reduced the awns that provided the mechanical connection, which likely leads to a low dispersal ability.

Other

Bidens campylotheca subsp. pentamera differs from the other two subspecies primarily in leaf shape, though subspecies waihoiensis also differs in the shape of the achenes. Subspecies pentamera has pinnate or bipinnate leaves with 5 to 9 leaflets, which are lobed. In contrast, the nominate subspecies campylotheca has pinnately compound leaves with only 3 to 5 leaflets and subspecies waihoiensis has bipinnate or tripinnatifid leaves with 5 to 9 leaflets dissected into linear segments. The achenes of subspecies pentamera are similar to subspecies campylotheca in being irregularly twisted or coiled without wings or awns (bristles). Those of subspecies waihoiensis, however, are straight with undulating wings and short awns.