Zinnia is a genus of plants of the tribe Heliantheae within the family Asteraceae. They are native to scrub and dry grassland in an area stretching from the Southwestern United States to South America, with a centre of diversity in Mexico. Members of the genus are notable for their solitary long-stemmed 12 petal flowers that come in a variety of bright colors. The genus name honors German master botanist Johann Gottfried Zinn (1727–59).

The Heliantheae are the third-largest tribe in the sunflower family (Asteraceae). With some 190 genera and nearly 2500 recognized species, only the tribes Senecioneae and Astereae are larger. The name is derived from the genus Helianthus, which is Greek for sun flower. Most genera and species are found in North America and South America. A few genera are pantropical.