Large-Flowered Coreopsis
Coreopsis grandiflora
Aster family (Asteraceae)

Description: This adventive perennial plant is about 2' tall, unbranched, and hairless. The leaves are arranged oppositely or alternately at intervals along the stem (usually the former). They are pinnatifid and deeply lobed. The leaf segments are linear and rather irregular; the terminal segment is usually the largest. A few leaves at the bottom or the top may be linear and lack lobes. These leaves are up to 3" long and 2" across, although the linear leaf segment are less than " across. At the apex of the plant, is a rather long and naked flowering stem with a single composite flower about 2" across. It consists of 6-12 yellow ray florets that surround numerous golden yellow disk florets. Each ray floret has 4-5 notches along the outer edge. This provides the composite flower with an attractive, somewhat ragged, appearance. The blooming period occurs during early to mid-summer and lasts about a month. This is little or no floral scent. The flowerbuds have a smooth, spherical appearance, and are olive green. The achenes are flat and rather oblong, with two have small scales at the apex. They are distributed to a limited extent by the wind. The root system has rhizomes, causing colonies to be formed.

Cultivation: The preference is full sun and dry conditions. This plant is typically found in a rather heavy soil containing clay or gravel. At a well-drained site, it is an easy plant to grow, and has few problems with foliar disease.

Range & Habitat: Large-Flowered Coreopsis occurs primarily in western Illinois and the Chicago area (see Distribution Map). This plant is originally from areas that lie west and southwest of Illinois, but it has since spread as an occasional escape from cultivation and other disturbances of modern development. In Illinois, it is a rather uncommon plant, but probably occurs in more areas than official records indicate. Habitats include upland areas of prairie (including prairie restorations), openings in rocky upland forests, thickets, glades, roadsides, and miscellaneous waste areas.

Faunal Associations: Like other coreopsis species, a wide range of insects are probably attracted to the flowers, including long-tongued bees, short-tongued bees, butterflies, and skippers. These insects usually seek nectar, although bees sometimes collect pollen. An oligolege of Coreopsis spp. is Melissodes coreopsis (Coreopsis Miner Bee). The larvae of the moths Tornos scolopacinarius (Dimorphic Gray) and Enychlora acida (Wavy-Lined Emerald) feed on the foliage or flowerheads. Such mammalian herbivores as rabbits, groundhogs, livestock, and probably deer occasionally consume the foliage as well.

Photographic Location: The photographs were taken at Meadowbrook Park in Urbana, Illinois.

Comments: Large-Flowered Coreopsis has showy flowers and attractive foliage. For these reasons, it is often available through the nursery trade and cultivated in gardens. This species can be distinguished from other Coreopsis spp. by the ragged appearance of the flower petals, and the linear pinnate leaves that occur along the stems, usually in opposite pairs. The species Coreopsis lanceolata (Sand Coreopsis) has ragged-looking petals, but its leaves are primarily lanceolate or oblanceolate in shape and confined near the base of the central stem. An eastern species that hasn't been observed in Illinois in natural areas, Coreopsis verticillata (Whorled Coreopsis), has leaves with a similar appearance, but they occur in whorls of three along the central stem. Also, the flowers of Whorled Coreopsis don't have a ragged appearance because their petals lack conspicuous outer notches. The narrowness of the leaves of Large-Flowered Coreopsis is somewhat variable, depending on the variety.

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