Description: This native perennial plant is 4-8' tall and usually unbranched, except for the slender flowering stems in the upper half. The opposite compound leaves are highly variable in appearance, but are usually divided into 3-5 narrow leaflets toward the base of the plant (oddly pinnate), but are smaller and lanceolate as they ascend up the flowering stems. The compound leaves near the base are up to 8" long and 6" across, while the upper leaves are less than 3" long and ¾" across. These leaves have smooth margins and are sparsely distributed along the stems, giving this plant an airy appearance. They are also hairless. Daisy-like compound flowers appear singly on the upper stems during late summer or early fall. Each composite flower is about 1½–2" across. There are 6-10 yellow ray florets surrounding numerous brown disk florets. There is no floral scent. The blooming period lasts about 1-2 months. The dark achenes are without tufts of hairs. The root system is fibrous and rhizomatous, often forming loose colonies of plants.

Cultivation: The preference is full or partial sun, and moist to mesic conditions. This plant isn't particular about soil type, and can be found growing in soil containing substantial amounts of loam, clay-loam, gravel, or sand. Tall Coreopsis tolerates competition from other plants and is easy to grow. In moist disturbed locations, it can become aggressive. Mature plants tolerate some drought, and foliar disease is rarely a significant problem.

Range & Habitat: Tall Coreopsis is occasional to fairly common in most counties of Illinois, but it is uncommon or absent in NW and SE Illinois. Habitats include moist to mesic black soil prairies, sand prairies, savannas and sandy savannas, thickets, seeps, bluffs, limestone glades, abandoned fields, and along railroads and roadsides. It responds well to fire in areas where shrubby vegetation and trees are encroaching.

Faunal Associations: The flowers attract long-tongued bees and short-tongued bees primarily, including bumblebees, Epeoline Cuckoo bees, Miner bees, large Leaf-Cutting bees, Halictine bees, and Panurgine bees. Other insects that occasionally visit the flowers include wasps, bee flies and other flies, butterflies, skippers, and the Goldenrod Soldier Beetle (Chauliognathus pennsylvanicus). The caterpillars of some moths feed on the foliage, including Tornos scolopacinarius (Dimorphic Gray) and Enychlora acida (Wavy-Lined Emerald). Mammalian herbivores occasionally eat this plant, especially the tender growth of young plants earlier in the year.

Comments: This is the tallest coreopsis, which blooms later than other members of the genus. It also has smaller flowers with dark brown centers, rather than the yellow centers of other species. Tall Coreopsis is more impressive when it occurs in colonies, rather than as a stand-alone specimen. Each plant tends to sway with the passage of every breeze during a sunny afternoon, exerting a hypnotic effect.