Any ornamental summer-blooming plant of the genus Coreopsis, commonly known as tickseed, in the composite family, consisting of about 100 species of annual and perennial herbaceous plants native to North America. Members have flower heads with yellow disk flowers and yellow, pink, white, or variegated ray flowers. The heads are solitary or in branched clusters, and some varieties have double flowers. Golden coreopsis (C. tinctoria) is a popular garden plant; swamp tickseed (C. rosea) is grown in wildflower gardens.
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Tickseed is the common name for Coreopsis, a group of 35 species of herbs in the family Asteraceae and genus Coreopsis. Many of them are used in cultivation. Twenty-eight species are native to North America and the others come from Central and South America. The flowers are usually yellow with a toothed tip. They have showy flower heads with involucral bracts in two distinct series of eight each, the outer being commonly connate at the base. The name is derived from the Greek word koris, meaning bedbug, from the shape of the achene. The plants are also popularly called "Calliopsis."