Bidens amplectens

Bidens amplectens is a member of the sunflower family (Asteraceae). It is an herb with branched stems, from 1.5 to 3 m (5 to 10 ft) tall. It has sparsely pubescent leaves that are pinnately compound, 9 to 15 cm (14 to 22 in) long with 3 to 5 leaflets. Cymes with lateral branches have 10 to 30 flower heads. Ray florets are yellow, 7 to 9 per head, and disk florets are 40 to 60 per head with yellow corollas. Achenes (dry fruit) are gray, straight, wingless, 5 to 8 mm (0.2 to 0.3 in) long and 1 mm (0.04 in) wide, sparsely setose (bristly) on margins and faces. == Life history ==

Bidens amplectens is a short-lived annual or perennial dicot herb. This species' lifespan is between 1 and 10 years. Little is known about the life history of Bidens amplectens. Flowering was observed in April, May, October, and November. Bidens amplectens' pollination vectors, seed dispersal agents, specific environmental requirements, and limiting factors are unknown. Bidens amplectens is known to hybridize with Bidens torta, another flower native to O'ahu. == Ecology ==

Diet Bidens amplectens is a photosynthetic autotroph. Pollinators Features of the Bidens genus’ flowers indicate pollination by birds, however, this has not been observed in nature. Habitat The habitat for Bidens amplectens includes cliffs and talus slopes in lowland dry shrubland on the windward side of the Waiʻanae mountains. The coastal ecosystem on O'ahu includes mixed herblands, shrublands, and grasslands, from sea level to 980 ft (300 m) in elevation. It is generally within a zone above the influence of waves to within 330 ft (100 m) inland. The coastal vegetation zone is typically dry, with annual rainfall of less than 20 in (50 cm). Windward rainfall may be higher. Biological diversity is low to moderate in this ecosystem. It may include some specialized plants and animals. The entirety of the species is restricted to the island of O'ahu. == Conservation ==

Population size There are currently 10 populations of Bidens amplectens totaling fewer than 500 individuals. Historically, this species was fairly common. In 2003, the widespread population was estimated to total fewer than 1,000 individuals. Last recorded, there are about 10 populations of Bidens amplectens. Seven of these populations in similar locations have numbers ranging from 10 individuals to more than 100 individuals. Three populations were observed elsewhere, numbered between 25 and 56 individuals. Listing under the Endangered Species Act Bidens amplectens was first listed as a candidate for protection under the Endangered Species Act as threatened in 2004. The final rule for the species listed it as endangered under the ESA in September 2012, along with 22 other species on O'ahu. At listing, critical habitat was established for the plant in two habitat types (1,508 ac, 607 ha). Species Status Assessment Not available for this species. Recovery plan The draft recovery plan for Bidens amplectens is in preparation. Recommendations for future actions There are recommended actions for each threat against Bidens amplectens. Authorities should continue to survey for Bidens amplectens in historical locations and potentially suitable habitats. Suitable habitat may be affected in the future by climate change which must be accounted for. There is a need for control of harmful nonnative invasive plants that compete with Bidens amplectens. As fire is a major threat, conservationists must develop and put in place fire prevention management plans. As herbivory is another major threat, exclosures or strategic fencing at all populations of Bidens amplectens should be constructed. Similarly, implementation of effective control methods for rats is necessary. For preservation of this species, collection of seeds for storage and propagation efforts is highly important. These seeds can be used for maintenance and reintroduction. There is a high need to start planning and contribute to enacting ecosystem-level restoration and management for this species. There is an interim recovery outline for the island of O'ahu that includes Bidens amplectens and all other endemic species. The outline is provided by the US Fish and Wildlife Service. The recovery outline suggests many of the actions listed by the HPPRCC plan. It lists many recovery efforts in place on the island, though most are small or underfunded. The Final Recovery Plan for O'ahu and Multi-Island listing is intended to be in place in 2026. ==References==