I grew Bidens cernua from seed a few years back. I had lots of success with germination, so I potted them and they bloomed like crazy. Then I planted them in the ground at the end of summer. I was so proud of myself and bragged to a botanist I know. "Uh, Mike. Bidens species are annuals." Oops! Since then I haven't done anything to keep it going, but every now and then one will emerge and bloom.

My totally unscientific hunch is that since annuals complete their life cycle in one season, they have to be prolific nectar and pollen producers. They can't afford a bad year! That might be why they are so popular with pollinator insects. I have a lot of the annual Jewelweed that self seeds every year here and it is a big hit with the hummingbirds and bees.

Bidens pilosa is an alien everywhere in the US, and I understand that it is aggressive and can become a problem. That "tickseed" reference in the common names of different plants refers to the size and shape of the seed, and also to the "stickiness" of the seeds. There are little barbs on the seeds that cause them to stick to clothing and fur.

Mike

These two species are more common in the South, and are pretty showy.

Bidens aristosa
https://www.prairiemoon.com/bidens-aristosa-swamp-marigold-prairie-moon-nursery.html

Bidens coronata
https://www.prairiemoon.com/bidens-coronata-tall-swamp-marigold-prairie-moon-nursery.html

"Swamp Marigold" sounds a lot better than "Beggar ticks!"

Those two occur up here, too. Maybe I will give them a try. They like it wet.

Mike