Purple Coneflower (Echinacea purpurea) of the Sunflower or Composite (Asteraceae) family is an erect herbaceous perennial with large, showy, terminal flowerheads. The genus name is derived from a Greek word for “hedgehog” in reference to the spiny bracts that share the receptacle with the ray and disk florets. The specific epithet is Latin for “purple,” the color of the ray florets. In the US, the species is common in Arkansas, Missouri and Indiana with more limited occurrence in surrounding states and from Alabama into New England. In Arkansas, plants grow statewide except for the lowlands of the Mississippi Alluvial Plain and West Gulf Coastal Plain. Habitat preference is sunny to partially sunny sites on moist, well drained soils of prairies, open woodlands and borders, and rights-of-way. Other common names include Eastern Purple Coneflower and Broad-Leaved Purple Coneflower.
Mature plants develop a central knobby rootstock comprising a clump of shallow “root stubs” supported by fleshy, whitish roots. The root stubs have actively growing crowns with new growth, as well as dormant stems from previous growing seasons. Growth that does not include a stem is flattened and fan-like and produces basal leaves; growth that includes a stem is terete and reproductive, ultimately bearing one or more terminal heads.
The pale-green, stout, erect stems to 3+ feet tall are typically hirsute, uncommonly partially or totally glabrous. Stems taper from a ¼-inch-diameter base, before flaring to the receptacle in support of the flowerhead. Robust plants produce axillary branches at mid-stem that may be 1½ feet long and overtop the main stem. Stems bear single terminal flowerheads, with that of the main stem typically the largest. Stem leaves are generally alternate, but may be sub-opposite to opposite, especially on more robust plants. The upper one-third to one-fifth of stems and branches tends to be leafless. Dead stems, branches and heads persist into the new growth-year.
Leaves vary from small, early, heart-shaped basal leaves to larger basal and stem leaves that are broadly lanceolate below to narrower above. Petioles of basal and lower stem leaves are especially long and may exceed the length of the leaf blade. Leaf bases may be rounded or tapered with the blade extending as narrow wings along the petiole. Larger leaves grow to 14 inches long, including 8-inch petioles, and to 4+ inches wide, typically widest below the middle. Blade margins tend to be entire (smooth) on smaller leaves, but jagged and irregularly serrate on larger leaves. Both upper and lower leaf surfaces may be uniformly covered with dense minute hairs, feeling equally rough, or the upper surface may be markedly less pubescent. Primary veins consist of a straight midrib and a pair of secondary veins that arch from the leaf base to the tip. Veins, including prominent tertiary veins, are recessed above and expressed below.
The blooming period may extend from late May through July. Early in the growth of flowerheads, buds are spherical with a full cover of hirsute, leafy, lanceolate to linear bracts (often termed phyllaries) imbricated in several series. By flowering time, the phyllaries have become spreading to recurved, resulting in a tight, leafy, saucer-shaped involucre. The longer outermost bracts expand to 1¼ inches long and ⅛ wide.
Flowerheads, 1½ to 4 inches across in bloom, have a central disk of numerous, closely packed disk florets surrounded by 10 to 20 large and prominant ray florets. As in all Composites, bloom sequence is centripetal––from the perimeter toward the center. Disks may be 1½+ inches wide and 1¼+ inches tall, having matured from a flat-topped head at bud-stage to a rounded cone as the final disk florets develop.
Ray florets have pink to pale purple, oblong ligules––the showy portion of the ray floret–– that are spreading to recurved and even drooping. Ligules vary from 1¼-3¼ inches long and ¼-¾ inch wide, with a rounded, notched tip. Ray flowers are infertile.
Disk florets have tubular corollas with 5 triangular stubby lobes, 5 stamens (filaments + anthers), and a single pistil (inferior ovary + style + stigma). Corollas are to 3/16 inch long and 1/32 inch wide. The elongate, dark anthers are fused into a ring surrounding the style. With the anther ring exserted above the corolla, the style pushes through the ring moving pollen from inside the anthers to above the corolla. With pollen dispersed, anthers wither back into the corolla and the now-exserted style bifurcates and recurves to expose linear stigmatic surfaces. At anthesis, corolla lobes, anther ring and stigma are typically reddish purple, but may trend toward green. Pollen is yellow.
Each disk floret is subtended by a sharply pointed, spike-like receptacular bract, to ⅝ inch long and 1/32 wide. The green boat-shaped lower portion of the bract clasps the developing disk floret. The orange, spike-like upper portion gives the central disk a golden glow. Corollas, stamens and styles all remain below the tips of the bracts. The central disk is very prickly during anthesis and remains prickly as a dried head.
In late summer into fall, the prickly heads, stems and branches become brown to black and persist into the next growing season. The flattened, four-sided, one-seeded achenes are mostly glabrous with a concave crown tipped with several short teeth. Achenes are less than ¼ inch long. They are dispersed by birds, small mammals and surface water flow.
Purple Coneflower, with its large and colorful flowerheads, is an excellent perennial for a formal or informal garden. This long-blooming, mostly erect, sturdy plant prefers a sunny area with well-drained mesic soil, but will also bloom nicely in partial shade. It works well as a specimen plant, in mass plantings or as a companion plant with other summer-blooming perennials. It may self-seed too freely in some sites, but plants are easily removed (shallow rootstock). Vegetative growth, flowers and seeds provide food for many insects, birds and small mammals––plants are a favorite of Pearl Crescent butterflies and Goldfinches. Excellent for arrangements when in bloom or dried.
Four other species of Echinacea occur in Arkansas: Pale Purple Coneflower (Echinacea pallida), Yellow Coneflower (Echinacea paradoxa var. paradoxa), Sanguine Purple Coneflower (Echinacea sanguinea), and Glade Coneflower (Echinacea simulata). Pale Purple Coneflower, Sanguine Purple Coneflower, and Glade Coneflower all have narrow leaves and strap-like pink to pale purple drooping ligules. Purple Coneflower is readily distinguished by its broad petiolate leaves and wider, more spreading ligules.
Article and photographs by ANPS member Sid Vogelpohl