Coreopsis, commonly called tickseeds, is a genus of flowering plants in the family Asteraceae, tribe Coreopsideae. Established by Linnaeus in 1753, the genus comprises annuals, perennials, subshrubs, and shrubs typically growing between 10 and 120 centimetres tall. The common name "tickseed" echoes the genus name itself, which derives from the Ancient Greek words for "bedbug" and "view" — a reference to the small, flat, insect-like shape of the achene fruits.
Flower heads are showy and radiate, with involucral bracts arranged in two distinct series of eight each. Most species bear bright yellow ray flowers with toothed tips, though some produce striking red-brown, bicolor, pink, or even white blooms. Fruits are flattened cypselae, often thin-margined or winged, facilitating wind dispersal.
The genus is native to the Americas, with nearly all of its roughly 39–100 recorded species (depending on the taxonomic treatment) originating in North, Central, and South America. Plants of the World Online currently accepts 39 species organized into 11 sections. The genus is considered paraphyletic and is closely related to Bidens. With 168 descendant taxa recorded in GBIF, Coreopsis encompasses significant morphological diversity across its range, from prairie annuals of the Great Plains to subshrubs of the American Southwest.
Etymology
The genus name Coreopsis is formed from two Ancient Greek words: koris (κόρις), meaning "bedbug," and opsis (ὄψις), meaning "view" or "appearance." The name alludes to the shape of the seed-like achene fruits, which resemble a small insect. The common name "tickseed" conveys the same idea in English. Linnaeus coined the name when he formally described the genus in Species Plantarum in 1753.
Distribution
Coreopsis is a New World genus, with virtually all species native to North, Central, and South America. North American species are particularly diverse and frequently colonize roadsides, open fields, and disturbed habitats, often self-sowing freely. The American Southwest hosts a notable concentration of species including C. alata, C. bigelovii, C. basalis, and C. tinctoria. Several ornamental species — most notably C. grandiflora, C. lanceolata, C. auriculata, and C. tinctoria — have been introduced and naturalized well beyond their native ranges through horticultural use. In Switzerland, for example, C. grandiflora and C. lanceolata are both documented as established plants in the national checklist.
Taxonomy
Coreopsis L. was established by Linnaeus in 1753 (Sp. Pl. 2: 907) and is currently placed in the tribe Coreopsideae within the family Asteraceae, order Asterales. Plants of the World Online accepts 39 species arranged into 11 sections: Anathysana, Calliopsis, Coreopsis, Electra, Eublepharis, Gyrophyllum, Leptosyne, Pseudoagarista, Pugiopappus, Silphidium, and Tuckermannia. The genus is considered paraphyletic and is closely allied to Bidens. GBIF records 168 descendant taxa under the genus (GBIF key 3133864). SEINet lists over 50 species with strong representation in the American Southwest.
Ecology
Coreopsis species are valuable components of native plant communities. Their flowers are rich in nectar and pollen and attract a wide range of pollinators including butterflies, bees, hover flies, and wasps. The plants also support specialist herbivores: larvae of the moth Coleophora acamtopappi feed on Coreopsis. Many species grow from rhizomatous or cormiform bases, an adaptation that allows persistence in disturbed, variable, or drought-prone environments typical of open grasslands, prairies, and the American Southwest. North American species are frequent colonizers of roadsides and open fields.
Cultivation
Coreopsis plants are straightforward to cultivate and widely grown as garden ornamentals. They thrive in full sun with well-drained soil and tolerate dry conditions once established. Both annual and perennial species are available, with perennials generally hardy to USDA zones 6b–7a. Deadheading spent flowers prolongs the blooming season and prevents unwanted self-seeding. The cheerful, long-lasting flowers attract butterflies and bees, making Coreopsis a popular choice for pollinator gardens. Several species, including C. grandiflora, C. lanceolata, and C. tinctoria, are also grown as cut flowers.
Cultural uses
In 1991, the Florida state legislature designated all species of Coreopsis collectively as the state wildflower of Florida — an unusual distinction conferred on an entire genus rather than a single species. In the Victorian language of flowers, Coreopsis symbolizes "always cheerful," while C. arkansa specifically is associated with "love at first sight." Several species, particularly C. tinctoria, have historical use as a source of golden-yellow dye. Coreopsis species are widely used in wildflower meadow plantings, roadside restoration, and pollinator habitat programs across North America.
Conservation
No Coreopsis species appear in the IUCN Global Invasive Species Database, and the genus as a whole is not considered globally invasive. Individual species may have localized conservation concerns in parts of their native range, but no genus-level conservation status is recorded in the sources consulted.
