These plants range from Template:Convert in height. The flowers are usually yellow with a toothed tip, but can also be yellow-and-red bicolor or pink.<ref name=":0">Template:Cite web</ref> They have showy flower heads with involucral bracts in two distinct series of eight each, the outer being commonly connate at the base. The flat fruits are small and dry and look like insects.
Coreopsis is a variable genus closely related to Bidens. In fact, neither Coreopsis nor Bidens, as defined in the 20th century, is strictly monophyletic. Coreopsis is best described as paraphyletic. Previously (1936), Coreopsis was classified into 11 sections and 114 species, but the African species were subsequently reclassified as Bidens, leaving the North and South American species, some 75–80 in all, under Coreopsis. 45 species are in the 11 North American sections, and the remaining 35 are in the South American section Pseudoagarista. The North American species fall into two broad groups, with 5 sections and 12 species in Mexico and North America and the remaining 5 sections and 26 species in Eastern North America.<ref name=Kim/>
One classification (GRIN) of the genus consists of eleven sections,<ref name="GRIN">Template:Cite web</ref> shown by cladistic relationships with number of species in parentheses.<ref name="Kim" />
North American Coreopsis can be found in two habitats in the wild, growing along roadsides and open fields throughout the Eastern United States and Canada. In this environment the plant will self-sow.
Ecology
Coreopsis species are a source of nectar and pollen for insects.<ref name=":0" /> The species is known to provide food to caterpillars of some Lepidoptera species, including Coleophora acamtopappi.
Cultivation
Coreopsis can grow in a garden as a border plant, or in a container, preferring well-drained soil. Deadheading the flowers ensures it does not become weedy. Using the U.S. Department of Agriculture (USDA) hardiness zones will identify what soil and climate is preferred for different cultivars or species.<ref>Template:Cite web</ref> Notable species found in cultivation are C. grandiflora and C. verticillata, as well as their various cultivars.
The sunny, summer-blooming, daisy-like flowers are popularly planted in gardens to attract butterflies. Both annual and perennial types are grown in the home garden (USDA hardiness zone 7a/6b).<ref name=":0" /> In the Mid-Atlantic region, insects such as bees, hover flies, and wasps are often observed visiting the flowers.<ref name=":0" />
