Thelesperma is a genus of North American and South American plants in the cosmos tribe within the sunflower family. Greenthread is a common name for plants in this genus. Members of the genus are used by a number of the southwestern Native American peoples as a tea; as such, it is sometimes called "Navajo tea," "Hopi tea," etc. T. megapotamicum contains luteolin. It also appears that many of the species contain a very similar chromatographic profile, and thus may contain very similar profiles of flavenoids. The genus is closely related to parts of Coreopsis and to certain North American Bidens species (including Bidens coronata and Bidens comosa).