a genus of annual or perennial herbs or subshrubs of the family Compositae. The leaves are opposite or entire. The inflorescences are generally large solitary heads; the receptacle is tunicate. The ray flowers are brightly colored, ranging from white, yellow, and orange to red and purple. The disk flowers range in color from yellow to brown-red.
There are 17 species, distributed at elevations to 2,550 m in southwestern North America and in Central America. One species occurs in South America. Several species of zinnia have long been raised as garden ornamentals. Especially popular is Z. elegans, which is native to Mexico and was imported to Europe in the 18th century. An herbaceous annual measuring 30–90 cm tall, Z. elegans has single or double flower heads and an erect branching stem. The species is divided, according to the type of inflorescence, into seven groups. Two of the groups—giant forms (or dahlia-flowered forms) and Liliputians—occur in the USSR. Giant zinnias reach 70 cm in height, and their inflorescences measure 10–14 cm across. Varieties include King Orange, Pink, and Scharlach. Liliputian zinnias are low-growing plants, with inflorescences measuring 3–6 cm across. Varieties include Red Cap and Tom Thumb.
Zinnias thrive in various soils; they are resistant to drought but not to frost. In the central part of the European USSR the seed is sown in protected ground in April or March; the seedlings are set out after the spring frosts. Flowering occurs eight to ten weeks after sowing. Zinnias are raised for cut flowers or as large flower groups on lawns, as plantings in flower beds, or as borders.