Bidens frondosa

It is widespread across much of Canada, the United States, and Mexico[2][3][4] It is known in many other parts of the world as an introduced species, including Europe, Asia, Morocco, and New Zealand.

[9] Bidens frondosa grows best where there is ample soil moisture and sun, especially in areas where something has disrupted the existing plant community leaving bare ground.

[12] The defoliating caterpillar of Hadjina chinensis, which is limited to Bidens species, has been observed on this plant.

[14] Bidens frondosa is an annual herb, usually growing to 20–60 cm (8–24 in) tall, but it may reach 1.8 m (6 ft).

The fruit is a flat black or brown barbed cypsela up to a centimeter long which has two obvious hornlike pappi at one end.

Bidens frondosa flowering head
Bidens frondosa leaf