Know Your Natives – Tall Coreopsis

Tall coreopsis or tall tickseed (Coreopsis tripteris) of the aster or sunflower family (Asteraceae) is the tallest of eight coreopsis species native to Arkansas. It occurs primarily from eastern Texas north to Iowa and Wisconsin and east to Pennsylvania and the Florida panhandle. In Arkansas, it grows throughout much of the state except for lower areas of the Mississippi Alluvial Plain and West Gulf Coastal Plain. The genus name originates from Greek words meaning “like a bug,” in reference to the bug-like appearance of the fruit. The specific epithet is from Greek words for “three” and “wings” in reference to the plant’s trifoliate leaves. Preferred habitats include sunny to partially sunny sites in various well-drained yet mesic soils in prairies, rights-of-way, thickets, open woodlands, and wood margins, often along creeks.

Tall coreopsis is a herbaceous perennial that develops a tough caudex from which long ropy roots and rhizomes radiate. Rhizomes are segmented; each segment is subtended by an encircling growth-ring marked by a brown triangular bract. New clonal plants form at the ends of rhizomes. Caudices support one to several erect to leaning stems up to eight or more feet tall, unbranched except above in the inflorescence. Stems are slender, round, and hollow, glaucous when young, light green and glabrous, with slight rounded ridges. They bear widely spaced, opposite, decussate pairs of mostly compound, trifoliate leaves, about 2-3 inches apart. Petioles of the paired leaves have broadened bases which extend to form a ring around the stem.

Photo 1: This clonal rootstock has a “parent-rhizome” extending to lower left and a single stem extending to upper right. Rootstock has ropy roots and segmented new rhizomes and stems.

Trifoliate leaves measure about 5 inches long (including 1+ inch petioles) and 3¾ inches wide, with a central leaflet and two (sometimes four) opposite wide-spreading lateral leaflets. Leaflets are lanceolate, mucronate at the tips, the central leaflet to 3½ inches long, the laterals about 1 inch shorter. Lateral leaflets are sessile; central leaflets are stalked on petiolules* to ¼ inch long. Minute, soft pubescence (visible with magnification) covers upper and lower surfaces of leaf blades. Simple leaves occur in pairs at the base of floral branches, decreasing in size to become the bracts and bracteoles of the inflorescence. Crushed leaves have an anise scent.

Photo 2: In this late June photo, glaucous stems bear compound, trifoliate leaves with lanceolate leaflets. Stems have slight longitudinal ridges.
Photo 3: Compound leaves occur along the stem with simple leaves at and within the inflorescence. Secondary and tertiary veins are obscure. Photo – July 26.

The inflorescence, at the upper portion of the stem, consists of flowerheads supported by erect glabrous pedicels (to 1 inch), peduncles (to 2½ inches), and branches (to 6 inches). The lower branches tend to be longest. Blooming extends over a month in mid-summer. 

Photo 4: In this early August photo, the tall stems tend to lean. Flowerheads have a dark central disk.

At anthesis, flowerheads have a bowl-shaped, double involucre: an inner series of 6-10 yellow-green, broader, longer phyllaries, reflexed at their tips, and an outer series of narrower, bright green, ascending phyllaries.

Flowerheads are 1+ inch wide, with 6-10 bright yellow ray florets and 40-50+ disk florets. The showy ray florets are sterile, serving only to attract pollinators. Disk florets have reddish brown, tubular corollas (with five short, triangular, recurved lobes) and an equal number of stamens that become strongly exserted. Anthers are fused into a tube through which the style emerges, carrying and exposing the yellow pollen to pollinating insects. With pollen of the disk florets dispersed, the style divides and recurves to expose two elongate stigmatic surfaces. The central disk is flat before disk florets open, but becomes “prickly” as florets bloom sequentially from perimeter to center.

Photo 5: Pubescent inner phyllaries and linear-oblong outer phyllaries (brown tipped) can be seen on flowerhead at right. At left, corollas of sterile ray florets are fully extended while some disk florets are releasing pollen. One disk floret (upper left) has matured to show its bifurcated stigma.
Photo 6: Lower surface of flowerhead, right, shows dull yellow tips of the inner phyllaries at the base of the bright yellow ray florets as well as the green, ascending outer phyllaries. Flowerheads have been removed from pedicel/peduncle at left.

Disk florets that are fertilized form achenes (“cypselae” in the aster family) that vary in appearance depending on position within the central disk. Achenes at and near the perimeter are flattened, thin, and ovoid with narrow lateral wings as well as a concave and a convex side. Achenes at and near the disk center are elongate and wingless. All achenes are dark brown to black at maturity and truncate at apex and base. Seed dispersal is by wind and gravity, and sometimes subsequently by water.

Photo 7: Three disk florets are shown at left. On the flowerhead, three disk florets have exserted anther tubes and pollen has been released. Three maturing winged achenes (from a different flowerhead) are shown at lower left.

In a garden setting, tall coreopsis would be best suited for a natural area, due to its ability to develop colonies from rhizomes and self-seeding. Foliage and flowers are both attractive. Plants lean when bearing flowerheads due to the height of their slender stems. It is not bothered by deer.

Tall coreopsis, one of eight native Arkansas species in the genus, can be distinguished from the other species by a combination of its 1) height, 2) trifoliate compound leaves composed of lanceolate leaflets, 3) late period of bloom, and 4) reddish-brown central disk.

Article and photographs by ANPS member Sid Vogelpohl

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