Flowers. Bottomless lake, NM, US. Wild. 1998-06-01.
Thelesperma megapotamicum (Spreng.) Kuntze Engl.: Hopi tea greenthread, Indian tea, Navajo tea. Span.: cota. Bot. syn.: Bidens megapotamica Spreng., Thelesperma gracile (Torr.) Gray
The copyright information is here.
Henriette's herbal is one of the oldest and largest herbal medicine sites on the net. It's been online since 1995, and is run by Henriette Kress, a herbalist in Helsinki, Finland.