|Photo by Linda Langelo|
This plant is from the Asteraceae Family. There are 51 species of Bidens. There are other species such as Bidens pilosa which is an annual flowering all summer into fall.
Bidens has many common names such as beggarticks, black jack, burr marigolds, cobbler's pegs, Spanish needles, stickseeds and tickseeds. WOW! No wonder it is confused. Comparing Bidens to Ratibida columnifera or Prairie Coneflower which is a hardy perennial in eastern Colorado, the Ratibida has stopped blooming.