coastal beggarticks

Bidens hyperborea, the coastal beggarticks, is a rare annual herb in the family Asteraceae native to coastal wetland habitats of eastern Canada and the northeastern United States, where it occurs in salt marsh margins, tidal river banks, and brackish wetland edges. The species belongs to a complex of annual Bidens species adapted to disturbed, muddy, or seasonally flooded habitats, and can be difficult to distinguish from related taxa. Like other beggarticks, it produces small yellow flower heads followed by barbed achenes equipped with two to four awns, which catch onto fur, feathers, or clothing for animal-mediated seed dispersal, a strategy reflected in the common name. Bidens hyperborea is uncommon to rare throughout its range and is assessed as Least Concern by the IUCN, though it is considered a species of conservation concern in several states and provinces where it occurs. Coastal wetland habitats in eastern North America have experienced substantial reduction through filling, agricultural drainage, and development over the past century, and ongoing sea-level rise combined with saltwater intrusion threatens to alter the brackish wetland habitats where this species persists. The genus Bidens is distributed globally across temperate and tropical wetland habitats.